CN118291946A

CN118291946A - Thin film deposition method capable of improving deep hole filling uniformity

Info

Publication number: CN118291946A
Application number: CN202410728483.0A
Authority: CN
Inventors: 周洁鹏; 宋维聪
Original assignee: Shanghai Betone Semiconductor Energy Technology Co ltd
Current assignee: Shanghai Betone Semiconductor Energy Technology Co ltd
Priority date: 2024-06-06
Filing date: 2024-06-06
Publication date: 2024-07-05
Anticipated expiration: 2044-06-06

Abstract

The invention provides a film deposition method capable of improving deep hole filling uniformity, which comprises the following steps: s1: providing a deposition chamber for preheating; s2: introducing silicon-containing gas and oxidizing gas, wherein the flow ratio is more than 2, and depositing a silicon oxide protective film on the surface of the inner wall of the deposition chamber under the conditions that the pressure in the deposition chamber is 550-600 torr and the temperature is 400-550 ℃; s3: placing a substrate with a plurality of openings in a deposition chamber, introducing silicon-containing gas and oxidizing gas, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is more than 2, and depositing a first silicon oxide layer on the inner surfaces of the openings; s4: and introducing silicon-containing gas and oxidizing gas for a third preset time period, applying pulse radio frequency power to the deposition chamber, and simultaneously applying bias pulse power to the substrate to deposit a second silicon dioxide layer on the surface of the first silicon oxide layer, wherein the high frequency power of the pulse radio frequency power is 500-700 w, the low frequency power is 100-3000 w, and the bias pulse power is 200-400 w. The invention is beneficial to improving the uniformity of deep hole filling.

Description

Thin film deposition method capable of improving deep hole filling uniformity

Technical Field

The invention relates to the technical field of integrated circuit manufacturing, in particular to a thin film deposition method capable of improving deep hole filling uniformity.

Background

With the rapid development of memory and advanced packaging technologies, the through silicon via (TSV, through Silicon Via) process is becoming more and more widely used. And with the increasing aspect ratio of through-silicon vias, the challenges of the through-silicon via filling process are increasing.

The first step in the existing through-silicon via filling process is typically silicon dioxide film deposition, mostly filled with SACVD (sub-atmospheric film deposition) process. Because the film deposited by the SACVD process has poor compactness and has larger phase difference compared with the plasma enhanced deposition (PECVD) process, the existing method is to deposit a part by the SACVD process and then deposit a layer on the surface by the PECVD process so as to increase the compactness of the surface of the silicon dioxide film. However, the poor hole filling capability of the PECVD process can result in thicker filling of the upper part of the through silicon via, and the situation of early sealing of the upper part of the through hole as shown in fig. 1 can affect the filling of the subsequent metal film. Similar problems exist in processes involving deep hole filling at high aspect ratios (aspect ratios of 5 or more), such as trench gate fabrication, in addition to through-silicon via filling processes.

It should be noted that the foregoing description of the background art is only for the purpose of providing a clear and complete description of the technical solution of the present invention and is presented for the convenience of understanding by those skilled in the art. The above-described solutions are not considered to be known to the person skilled in the art simply because they are set forth in the background of the invention section.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, an object of the present invention is to provide a thin film deposition method capable of improving deep hole filling uniformity, which is used for solving the problems that the upper part of a through hole is filled thicker, the upper part of the through hole is sealed in advance, and the filling of a subsequent metal film is affected due to poor hole filling capability of the PECVD process in a manner that a layer of silicon oxide is deposited by the SACVD process and then a layer of silicon oxide is deposited by the PECVD process.

To achieve the above and other related objects, the present invention provides a thin film deposition method for improving deep hole filling uniformity, comprising the steps of:

s1: providing a deposition chamber, and preheating the deposition chamber;

S2: introducing a first preset time period of silicon-containing gas and an oxidizing gas into the deposition chamber, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is more than 2, and depositing a silicon oxide protective film on the surface of the inner wall of the deposition chamber under the condition that the pressure in the deposition chamber is 550-600 torr and the temperature is 400-550 ℃;

S3: placing a substrate with a plurality of openings in a deposition chamber, introducing silicon-containing gas and oxidizing gas with a second preset time period into the deposition chamber, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is more than 2, and depositing a first silicon oxide layer on the inner surface of the openings under the condition that the pressure in the deposition chamber is 550-600 torr and the temperature is 400-550 ℃;

S4: and (3) introducing a third preset time period of silicon-containing gas and oxidizing gas into the deposition chamber, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is greater than that in the step S3, the flow of the silicon-containing gas is smaller than that of the silicon-containing gas in the step S3, the pressure in the deposition chamber is kept at 2-10 torr, the temperature is 400-550 ℃, pulse radio frequency power is applied to the deposition chamber, bias pulse power is applied to the substrate at the same time, and a second silicon oxide layer is deposited on the surface of the first silicon oxide layer, wherein the high frequency power of the pulse radio frequency power is 500-700 w, the low frequency power is 100-3000 w, and the bias pulse power is 200-400 w.

Optionally, in steps S2 and S3, the flow rate of the silicon-containing gas is 2000sccm to 3000sccm, and the flow rate of the oxidizing gas is 12000 sccm to 20000sccm.

Optionally, in step S4, the flow rate of the silicon-containing gas is 1000 sccm-1200 sccm, and the flow rate of the oxidizing gas is 20000 sccm-24000 sccm.

Alternatively, in steps S2 and S3, the flow ratio of the oxidizing gas and the silicon-containing gas is 8.

Optionally, in step S4, the flow ratio of the oxidizing gas to the silicon-containing gas is 20.

Alternatively, the pulsed radio frequency power has a high frequency of 13.56MHz, a low frequency of 4Khz, and a bias pulse frequency of 2Mhz.

Optionally, the first preset time period is 25s-30s, the second preset time period is 100s-120s, and the third preset time period is 25-30s.

Optionally, the silicon-containing gas comprises TEOS and the oxidizing gas comprises one or more of oxygen, ozone, and water vapor.

Optionally, a gas spraying disk is arranged at the top of the deposition chamber, a base for placing a substrate is arranged in the deposition chamber, a pulse radio frequency power supply is connected with the gas spraying disk, and a bias pulse power supply is connected with the base.

Optionally, nitrogen gas of 40000sccm-45000sccm is introduced into the deposition chamber during the deposition process of steps S2 and S3 to maintain the pressure in the deposition chamber stable.

Optionally, step S4 includes an adjustment step of gradually decreasing the pulsed rf power and gradually increasing the bias pulsed power during deposition.

Optionally, the thin film deposition method further includes a step of adopting one of the following methods to reduce the growth rate of the silicon oxide layer on the upper surface of the opening;

a. Depositing photoresist on the upper surface of the substrate before the substrate is placed in the deposition chamber, wherein during the deposition process, the photoresist flows to the upper surface of the opening to consume part of the oxidizing gas;

b. Forming a macromolecular compound layer which does not react with the oxidizing gas and the silicon-containing gas on the upper surface of the opening of the substrate so as to occupy active sites on the upper surface of the opening;

c. In the deposition process of the step S2, adding silicon oxide etching gas with the flow rate less than one tenth of the flow rate of the oxidizing gas into the reaction gas;

d. the passivation process is performed on the top of the openings prior to placing the substrate in the deposition chamber.

As described above, the thin film deposition method capable of improving deep hole filling uniformity has the following beneficial effects: according to the film deposition method provided by the invention, the chamber is pre-deposited before the film deposition is carried out on the substrate, and the pulse power supply and the bias pulse power supply are introduced in the later deposition period, so that the difficulty of deep hole filling is reduced and the compactness of the deposited film is improved while the deposition efficiency is considered, the deep hole filling uniformity is improved, the upper part of the deep hole is prevented from being sealed in advance in the filling process, and the production yield is improved. The invention can be used for preparing the silicon through hole and can also be used for trench gate and other processes involving deep hole filling with high depth-to-width ratio.

Drawings

Fig. 1 is a schematic diagram showing the occurrence of overfill over-thickness during oxide layer deposition of through-silicon vias using prior art techniques.

Fig. 2 is a schematic cross-sectional view showing an apparatus for performing the thin film deposition method for improving deep hole filling uniformity according to the present invention.

FIG. 3 is a flow chart illustrating an exemplary method for depositing a thin film to improve deep hole filling uniformity.

Fig. 4 is a schematic cross-sectional view illustrating a silicon oxide layer formed on the surface of an opening according to an embodiment of the invention.

Fig. 5 is an electron microscopic view showing a silicon oxide layer formed on the surface of the opening at the opening in the comparative example of the present invention.

Fig. 6 is an electron microscope image of a silicon oxide layer formed on the surface of an opening in an embodiment of the invention.

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. As described in detail in the embodiments of the present invention, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.

For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. 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 figures. Furthermore, 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.

In the context of the present invention, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, as well as embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex. In order to make the illustration as concise as possible, not all structures are labeled in the drawings.

The present invention provides a thin film deposition method that can improve deep hole filling uniformity, which can be performed based on the apparatus shown in fig. 2. The thin film deposition methods of the present embodiment are all performed in the same chamber.

In the apparatus shown in fig. 2, there is included a deposition chamber 11, a gas shower plate 12 located at the top of the deposition chamber 11, and a susceptor 13 located inside the deposition chamber 11 and generally directly below the gas shower plate 12. The pulse radio frequency power supply is connected with the gas spraying disk.

Specifically, the deposition chamber 11 may be made of AL or an alloy thereof, and the deposition chamber 11 is generally grounded. The gas spraying plate 12 is used for guiding the reaction gas into the deposition chamber 11, and is connected to a pulse radio frequency power source, and the high-frequency power and the duty ratio of the pulse radio frequency power source can be adjusted according to the needs, for example, the high-frequency power of the pulse radio frequency power source in the embodiment is 500 w-700 w, and the low-frequency power is 100 w-3000 w. Under the action of the electric field excited by the radio frequency power supply, the reaction gas is decomposed into electrons, ions, active groups and the like. By adopting the pulse radio frequency power supply and optimizing the power and frequency of the pulse radio frequency power supply, the excessive bombardment of the plasma on the substrate can be reduced under the condition of the same ion energy (compared with the ion energy provided by continuous radio frequency power), the surface damage of a deposited film layer can be repaired, and the film quality can be improved. In other examples, a plurality of rf coils may be disposed on the exterior of the deposition chamber to apply auxiliary rf power to the deposition chamber to help further increase the plasma concentration and increase the film growth rate.

The susceptor 13 is used for carrying a substrate 14, such as a silicon wafer or a glass substrate, which is mainly exemplified in the present embodiment. The silicon wafer may be fixed on the susceptor 13 based on vacuum adsorption or electrostatic adsorption. The base 13 may be a nonmetallic disk such as a ceramic disk or a graphite disk, or may be a structure in which the surface of an aluminum alloy disk is plated with a ceramic layer. In this embodiment, a ceramic disk is taken as an example. Electrodes are provided in the base 13, which electrodes may be monopolar or bipolar. The electrodes are connected to a bias pulse power source, and the power and frequency of the bias pulse power source can be adjusted as required, for example, the power of the bias pulse in the embodiment is 200 w-400 w. By adjusting the power and the duty ratio of the pulse bias voltage, the temperature gradient between the inside and the surface of the substrate can be changed, so that the heat balance compensation effect between the inside and the surface of the substrate is changed, and the purpose of adjusting and controlling the deposition temperature is achieved. Meanwhile, the bombardment effect of high-energy ions can be obtained by utilizing the bias pulse, which is beneficial to improving the density of the film, improving the filling uniformity of the deep hole and avoiding the early closing of the upper part of the deep hole in the filling process. The support shaft at the bottom of the base extends to the outside of the deposition chamber, and can lift and/or rotate the substrate according to the requirement, thereby being beneficial to improving the uniformity of film deposition. Heating and/or cooling channels may also be provided in the base.

In some examples, a thermometer and/or pressure gauge may be provided within the deposition chamber to monitor temperature and/or pressure conditions within the chamber in real time.

In other examples, the invention may be implemented based on other approaches, such as bias pulses may be applied directly to the substrate, without limitation.

The general flow of the thin film deposition method for improving deep hole filling uniformity according to the present invention can be described with reference to fig. 3, and will be described below.

Step S1 is first performed: a deposition chamber is provided and preheated.

The deposition chamber may be a CVD chamber, the general structure of which may be seen with reference to fig. 2. The deposition chamber is typically cleaned, such as by a nitrogen purge, prior to performing the thin film deposition process. Preheating is carried out after cleaning. The preheating mode can be a mode of heating by a heater arranged in the base and/or a mode of heating by introducing heating gas. For example, the deposition chamber is first cleaned and preheated simultaneously by heating the gas, and then preheated to a desired process temperature, such as 400-550 c in this embodiment, such as 400, 450, 500, 550 c or any value in this interval, by heating the susceptor. In this embodiment, the temperature in the deposition chamber is preferably maintained in this temperature range throughout the deposition process to minimize adverse effects due to temperature fluctuations.

Step S2 is performed next: and introducing a first silicon-containing gas and an oxidizing gas for a first preset time period into the deposition chamber, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is more than 2, and depositing a silicon oxide protective film on the surface of the inner wall of the deposition chamber under the condition that the pressure in the deposition chamber is 550-600 torr and the temperature is 400-550 ℃.

This step can be regarded as the pre-deposition of step S3, and the deposition conditions, including the gas type, the gas flow rate, the pressure, and the like, are preferably the same as those of step S3, so that the workload of parameter adjustment can be reduced, and the deposition parameters of the next step can be optimized according to the deposition effect of the step. The pressure in the step is set at 550-600 torr, namely, a sub-normal pressure state. The deposition time is related to factors such as the type of gas, the flow rate of the gas, the thickness of the thin film to be deposited, and the like. For example, the silicon-containing gas in this embodiment includes silane (TEOS) at a flow rate of 2000-3000sccm (if introduced with a carrier gas, this flow rate refers to the total flow rate including the carrier gas flow rate, and the like), for example, 2000, 2500, 3000 or any value in this interval. The oxidizing gas may be any one or more of oxygen, ozone and water vapor, and in this embodiment, ozone (O3) is preferably used, the flow rate is 12000-20000sccm, and the flow rate ratio of the oxidizing gas to the silicon-containing gas is preferably 1:8. and nitrogen with the flow of 40000sccm-45000sccm is simultaneously introduced in the process of introducing the reaction gas so as to ensure that the pressure in the cavity in the deposition process is kept stable, which is very important for depositing a high-quality high-stability film. The nitrogen may also purge the reaction by-products. By adopting the conditions to deposit 100s-120s, the silicon oxide film with the thickness of about 1200A is deposited on the inner wall of the deposition chamber, so that the chamber pollution caused by bombardment of ions in the subsequent deposition process on the chamber wall can be prevented, and the silicon oxide layer made of the same material is formed on the surfaces of the inner wall of the chamber, the surface of the base and other components, thereby being beneficial to uniform heat conduction in the chamber, and being very important to improving the temperature uniformity in the deposition process and the film deposition uniformity.

Step S3 is performed next: placing a substrate with a plurality of openings in a deposition chamber, introducing silicon-containing gas and oxidizing gas into the deposition chamber for a second preset time, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is more than 2, and depositing a first silicon oxide layer on the inner surface of the openings under the condition that the pressure in the deposition chamber is 550-600 torr and the temperature is 400-550 ℃.

The embodiment is suitable for deep hole filling of various materials. For example, the substrate may be a wafer made of semiconductor materials such as silicon, germanium, silicon carbide, or other substrates such as glass, and the embodiment mainly uses a silicon wafer as an example, for example, a 12 inch substrate. The aspect ratio of the openings is typically above 10. The openings may be through-holes extending up and down (e.g., for use in making a silicon interposer), in which case the substrate is placed on a carrier plate. In this embodiment, the blind hole is mainly taken as an example of the open hole. The number of the openings is generally more than one, and the arrangement of the plurality of openings on the substrate depends on the device structure, and is not particularly limited. To facilitate subsequent film filling, the openings may be formed as funnel-like structures with upper openings larger than lower openings. The deposition conditions in this step are substantially the same as those in the previous step, for example, the silicon-containing gas is silane, the oxidizing gas is ozone, the silane flow rate is 2000sccm to 3000sccm, the ozone (O3) flow rate is 12000 to 20000sccm, and the optimum ratio of the flow rate to the silane flow rate is 1:8. and in this process, it is also preferable to pass nitrogen gas at a flow rate of 40000-45000sccm to stabilize the pressure during deposition. The reaction gas is introduced for 25-30s, and the thickness of the deposited first silicon oxide layer is 1000-2000A. By the step, a relatively thick silicon oxide layer can be deposited on the surface of the opening, and the production efficiency is improved.

Step S4 is performed next: and (3) introducing a third preset time period of silicon-containing gas and oxidizing gas into the deposition chamber, wherein the flow ratio of the oxidizing gas to the silicon-containing gas is greater than that in the step S3, the flow of the silicon-containing gas is smaller than that of the silicon-containing gas in the step S3, the pressure in the deposition chamber is kept at 2-10 torr, the temperature is 400-550 ℃, pulse radio frequency power is applied to the deposition chamber, bias pulse power is applied to the substrate at the same time, and a second silicon oxide layer is deposited on the surface of the first silicon oxide layer, wherein the high frequency power of the pulse radio frequency power is 500-700 w, the low frequency power is 100-3000 w, and the bias pulse power is 200-400 w. In a further example, the pulsed radio frequency power has a high frequency of 13.56MHz and a low frequency of 4Khz, and the bias pulse has a frequency of 2Mhz.

In this step, the silicon-containing gas is also silane, and the oxidizing gas is oxygen. The flow rate of the silicon-containing gas silane TEOS is 1000sccm-1200sccm, the flow rate of oxygen is 20000 sccm-24000 sccm, and the ratio of the flow rate to the TEOS is preferably 1:20 for a deposition time of 25s to 30s, the thickness of the deposited second silicon oxide layer is typically less than the thickness of the first silicon oxide layer, for example around 1000A. In this step, the pressure in the deposition chamber is 2-10 torr, for example, 2,3,4,5 … …, or any value in this region. Pulsed radio frequency power is applied to the deposition chamber while bias pulsed power is applied to the substrate to ionize the reactant gases and form an electric field around the substrate. Through the plasma reaction, the deposition process can be carried out under lower pressure, which is helpful for improving the compactness and uniformity of the deposited film, reducing the internal stress of the film, reducing the difference of the thickness of the film at the upper part and the lower part of the open pore, avoiding the early closure of the open pore and facilitating the subsequent filling. The morphology of the deep hole silicon oxide layer filled by the invention is shown in fig. 4, and the open holes can still keep larger openings without being sealed in advance, so that the subsequent film filling is greatly facilitated. For example, in the case of a through-silicon via process, PVD may then be used to fill the openings with a metallic conductive material. In the case of a trench gate process, a CVD process may then be used to deposit the polysilicon material. The present embodiment does not limit the specific type of device and thus the subsequent process steps are not developed in detail.

According to the film deposition method provided by the invention, the chamber is pre-deposited before the film deposition is carried out on the substrate, and the pulse power supply and the bias pulse power supply are introduced in the later deposition period, so that the difficulty of deep hole filling is reduced and the compactness of the deposited film is improved while the deposition efficiency is considered, the deep hole filling uniformity is improved, the upper part of the deep hole is prevented from being sealed in advance in the filling process, and the production yield is improved. The invention can be used for preparing the silicon through hole and can also be used for trench gate and other processes involving deep hole filling with high depth-to-width ratio.

In some examples, to further improve deep hole filling uniformity, the pulsed rf power and the bias pulse power may be adjusted during deposition in step S4 to taper the pulsed rf power and taper the bias pulse power. The pulse radio frequency power is gradually reduced in the later deposition period to gradually reduce the ion concentration, and the bias pulse power is gradually increased to compensate the condition of bias voltage reduction caused by accumulation of conductive particles around the substrate, so that the self-repairing function of the film is improved through the mutual matching of the two powers, and the film density is further improved to improve the film deposition uniformity.

In some examples, a reaction-inhibiting layer may be formed on the upper surface of the opening of the substrate to reduce the growth rate of the silicon oxide layer on the upper surface of the opening prior to placing the substrate in the deposition chamber. For example, in some examples, the reaction-inhibiting layer may be a photoresist layer that may be coated on an upper surface of the substrate, and after the photoresist-coated substrate is placed in the deposition chamber, the photoresist is softened by thermal melting at a high temperature of 400-550 ℃ in the deposition chamber, and flows toward the upper portions of the openings. In some cases, the substrate may also be rotated so that the reaction-inhibiting layer initially formed on the upper surface of the substrate gradually extends to the upper surface of the opening. After the reaction gas is introduced, the ozone contacted with the upper part of the open hole is reacted with the photoresist, and the reaction of depositing the silicon oxide layer can not be participated until the photoresist is completely oxidized, so that the growth speed of the silicon oxide layer on the upper part of the open hole can be reduced, and the uniformity of deep hole filling is improved.

In other examples, the reaction-inhibiting layer may be a cyclic compound, an aromatic compound, or the like, for example, one of a macromolecular compound such as methylene chloride, ethylene dichloride, octadecyl trichlorosilane, 1, 4-butylene oxide, ethanethiol, or the like. The preparation of the reaction-inhibiting layer varies with the material. For example, if the material selected is in a liquid or colloidal state, it may be applied to the upper surface of the substrate by coating, by means of elevated temperatures within the chamber, and/or by spinning the substrate so that it extends over the openings. In the case of a gaseous species, a gas containing a reaction-inhibiting material may be introduced into the deposition chamber to diffuse into the openings of the substrate before deposition begins. Due to the nature of these macromolecular materials, they adhere more to the upper part of the opening than to the lower part of the opening. These reaction suppressors will hinder the progress of the deposition reaction. During deposition, a large flow of 40000sccm to 45000sccm nitrogen gas was introduced into the deposition chamber to gradually purge the reaction suppressors to gradually release the reaction sites that were originally occupied. By the method, the deposition speeds of the oxide layers on the upper part and the lower part of the open hole tend to be the same, the upper part of the open hole is prevented from being sealed in advance, and the filling uniformity of the deep hole is improved.

In other examples, a small amount of etching gas may be introduced into the reaction gas during the deposition of step S3 and/or S4, for example, an etching gas having a flow rate less than one tenth of that of the oxidizing gas may be introduced into the reaction gas during the second half of the deposition of step S3, for example, a small amount of fluorine-containing gas may be introduced into the silicon-containing gas and the oxidizing gas. Because of the anisotropy of dry etching, the etching gas etches the silicon oxide formed at the upper part of the opening more than the silicon oxide formed at the lower part of the opening, and the purposes of slowing down the growth speed of the silicon oxide at the upper part of the opening and improving the filling uniformity of the deep hole can be achieved.

In other examples, the upper portion of the opening may also be passivated prior to placing the substrate in the deposition chamber, such as by hydrogen passivation, nitrogen plasma passivation, or oxygen ion implantation to passivate the upper portion of the opening by ion implantation techniques to reduce the growth rate of silicon oxide on the upper portion of the opening.

In order to make the technical scheme and advantages of the present invention more obvious, the present invention will be further described below with reference to specific embodiments.

Comparative example

1. A deposition chamber having AL as a chamber wall and a ceramic heating susceptor was provided, and the temperature in the chamber was controlled at 450 ℃.

2. Introducing silicon-containing gas TEOS and ozone (O3) into the chamber, wherein the introducing time is 25s, and depositing a silicon oxide film on the inner wall surface of the deposition chamber under the condition that the pressure in the chamber is 550torr, wherein the flow rate of silicon-containing gas silane TEOS is 2000sccm, the flow rate of ozone (O3) is 16000sccm, and the flow rate of ozone (O3) and TEOS are 1:8, and introducing 40000sccm of nitrogen gas to ensure stable pressure during the deposition, the deposition time was 100s, and the thickness of the silicon oxide film deposited on the inner wall surface of the deposition chamber was about 1200A.

3. Then placing a substrate (12-inch wafer), introducing silicon-containing gas TEOS and ozone (O3) into the chamber, wherein the introducing time is 25s, and depositing a first silicon oxide film on the surface of the wafer under the condition that the pressure in the chamber is 550torr, wherein the flow rate of silicon-containing gas silane TEOS is 2000sccm, the flow rate of ozone (O3) is 16000sccm, and the flow rate of TEOS is 1:8, and introducing 40000-45000sccm of nitrogen gas to ensure stable pressure during the deposition process, wherein the deposition rate is about 600A/min.

4. Introducing silicon-containing gas TEOS and oxygen (O2) into the chamber for 25 seconds, and maintaining the pressure in the chamber at 2torr, wherein the flow rate of silicon-containing gas silane TEOS is 1000sccm, the flow rate of oxygen is 20000sccm, and the flow rate ratio of the radio frequency power to TEOS is 1:20, the deposition rate is about 500A/min.

The morphology of the silicon oxide layer formed in this comparative example can be seen with reference to fig. 5. As shown in fig. 5, the silicon oxide layer at the opening of the opening protrudes toward the center of the opening to form a sharper lobe, which not only easily causes the lobe to obstruct diffusion of metal ions in the subsequent metal filling process to cause filling holes, but also easily causes tip discharge in case of trench gate fabrication for high-voltage devices, resulting in reduced device performance.

Examples

1. Providing a deposition chamber with an AL as a chamber wall and a ceramic heating base, and controlling the temperature in the chamber to be 450 ℃;

3. Then placing a substrate (a 12-inch wafer), introducing silicon-containing gas TEOS and ozone (O3) into the chamber, wherein the introducing time is 25s, and depositing a first silicon oxide film on the surface of the wafer under the condition that the pressure in the chamber is 550torr, wherein the flow rate of silicon-containing gas silane TEOS is 2000sccm, the flow rate of ozone (O3) is 16000sccm, and TEOS is 1:8, and introducing 400000sccm of nitrogen gas to ensure stable pressure during deposition, the deposition rate was about 600A/min.

4. Introducing silicon-containing gas TEOS and oxygen (O2) into the chamber for 25s, and under the condition that the pressure in the chamber is kept at 2torr, pulse radio frequency power high frequency power (13.56 Mhz) 500w and low frequency power (4 Khz) 100w to deposit a second layer of silicon oxide film, repairing the silicon oxide film deposited before the surface of the wafer, and introducing bias pulse power (2 Mhz) 200w, wherein the flow of silicon-containing gas silane TEOS is 1000sccm, the flow of oxygen is 20000sccm, and the flow ratio of the silicon-containing gas silane TEOS to TEOS is 1:20, the deposition rate is about 400A/min.

The main difference between this embodiment and the comparative example is that in this embodiment, in addition to pulsed rf power, bias pulsed power is introduced during the deposition of the second silicon dioxide layer on the wafer, and the parameters of these two powers are redesigned. The deposition rate of the film is reduced due to the bias voltage, but the performance of the film is enhanced.

The morphology of the silicon oxide layer formed in this embodiment may be as shown in fig. 6. As can be seen from fig. 6, in the silicon oxide layer prepared in this embodiment, the end surface of the silicon oxide layer at the opening of the opening forms a circular arc chamfer, so that the opening surface of the opening is still funnel-shaped, which is helpful for the subsequent film filling.

Based on example 1, the inventors conducted a number of experiments by adjusting the conditions of gas flow rate, deposition time, pressure in the chamber, and the like. The experimental surface shows that under the condition that the conditions provided by the invention are met, films deposited by different parameter combinations show similar deposition characteristics, the morphology of the silicon oxide layer at the opening of the opening is the morphology shown in figure 6 except for the difference in thickness of the deposited films, and the morphology is not developed one by one.

In summary, the film deposition method provided by the invention is characterized in that the chamber is pre-deposited before the film deposition is carried out on the substrate, and the pulse power supply and the bias pulse power supply are introduced in the later deposition period, so that the difficulty of deep hole filling is reduced and the compactness of the deposited film is improved while the deposition efficiency is considered, thereby being beneficial to improving the deep hole filling uniformity, avoiding the early closure of the upper part of the deep hole in the filling process, and being beneficial to improving the production yield. The invention can be used for preparing the silicon through hole and can also be used for trench gate and other processes involving deep hole filling with high depth-to-width ratio. The invention can be used for filling the silicon through hole and manufacturing the trench gate. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. A film deposition method capable of improving deep hole filling uniformity is characterized by comprising the following steps:

s1: providing a deposition chamber, and preheating the deposition chamber;

2. The thin film deposition method according to claim 1, wherein in steps S2 and S3, the flow rate of the silicon-containing gas is 2000sccm to 3000sccm, and the flow rate of the oxidizing gas is 12000sccm to 20000sccm; in the step S4, the flow rate of the silicon-containing gas is 1000 sccm-1200 sccm, and the flow rate of the oxidizing gas is 20000 sccm-24000 sccm.

3. The thin film deposition method according to claim 2, wherein in steps S2 and S3, a flow ratio of the oxidizing gas to the silicon-containing gas is 8; in step S4, the flow ratio of the oxidizing gas to the silicon-containing gas is 20.

4. The thin film deposition method according to claim 1, wherein the pulsed radio frequency power has a high frequency of 13.56MHz, a low frequency of 4Khz, and a bias pulse frequency of 2MHz.

5. The thin film deposition method according to claim 1, wherein the first preset time period is 25s to 30s, the second preset time period is 100s to 120s, and the third preset time period is 25s to 30s.

6. The thin film deposition method according to claim 1, wherein the silicon-containing gas comprises TEOS and the oxidizing gas comprises one or more of oxygen, ozone, and water vapor.

7. The thin film deposition method according to claim 1, wherein a gas shower plate is provided at the top of the deposition chamber, a susceptor for placing a substrate is provided inside, a pulsed radio frequency power supply is connected to the gas shower plate, and a bias pulsed power supply is connected to the susceptor.

8. The thin film deposition method according to claim 1, wherein nitrogen gas of 40000sccm to 45000sccm is introduced into the deposition chamber during the deposition of steps S2 and S3 to stabilize the pressure in the deposition chamber.

9. The thin film deposition method according to claim 1, wherein step S4 includes a step of adjusting the pulse radio frequency power to be gradually reduced and the bias pulse power to be gradually increased during the deposition.

10. The thin film deposition method according to any one of claims 1 to 9, further comprising a step of adopting one of the following methods to reduce a growth rate of the silicon oxide layer on the upper surface of the opening;

depositing photoresist on the upper surface of the substrate before the substrate is placed in the deposition chamber, wherein during the deposition process, the photoresist flows to the upper surface of the opening to consume part of the oxidizing gas;

Forming a macromolecular compound layer which does not react with the oxidizing gas and the silicon-containing gas on the upper surface of the opening of the substrate so as to occupy active sites on the upper surface of the opening;

In the deposition process of the step S2, adding silicon oxide etching gas with the flow rate less than one tenth of the flow rate of the oxidizing gas into the reaction gas;

the passivation process is performed on the top of the openings prior to placing the substrate in the deposition chamber.