TWI670385B - Film forming method - Google Patents

Abstract

The invention belongs to the technical field of semiconductor processing, and in particular relates to a film forming method. The film forming method comprises a loop performing a first sputtering stage and a second sputtering stage until the thickness of the film satisfies a setting requirement; wherein, in the first sputtering stage and the second sputtering stage, a pulse direct current is applied to the target Power; and, by setting the duty ratio of the pulsed DC power used in the first sputtering stage and the duty ratio of the pulsed DC power used in the second sputtering stage, respectively, the density and stress of the film are increased. The film forming method provided by the invention can simultaneously realize high-density and more stress film deposition under the premise of ensuring process stability and process cost, so as to meet the demanding requirements of the advanced integrated circuit process for film performance, and at the same time Reduce the cost of more advanced processes and the difficulty of process solutions.

Description

Film forming method

The invention belongs to the technical field of semiconductor processing, and in particular relates to a film forming method.

In recent years, with the large-scale development of integrated circuits, the critical dimensions of wafers have been shrinking, and the challenges of copper interconnect manufacturing processes are increasing. In order to ensure the compactness and structural integrity of copper interconnect structures below 16 nm and smaller, more advanced hard mask technology is required. In more advanced manufacturing processes, Hardmask's primary role is to maintain the graphical integrity of copper and vias in softer ultra-low-k dielectric materials. However, as wafer processing sizes continue to shrink, traditional hard mask layers (such as TiN layers) cannot be adapted to more advanced integrated circuit processes due to various problems. On the one hand, the conventional hard mask film has a lower density, and it is required to deposit a thicker thickness when preparing the film, which greatly increases the aspect ratio of the etched deep hole (Via) and increases the subsequent metal conductive layer in the deep hole. The difficulty of a series of processes such as filling in. On the other hand, the conventional hard mask process film is subjected to compressive stress (compressive stress) after deposition, which may cause deformation or collapse of a narrow copper pattern in the dielectric film. Therefore, only TiN hard masks with more compact and more stress (the positive direction is larger, 0 means no stress, negative is compressive stress, positive value is tensile stress) can be adapted to the more advanced integrated circuit process. .

In the integrated circuit manufacturing process, physical vapor deposition (PVD) is widely used to deposit a variety of different metal layers, hard masks and other related material layers. However, with the above-mentioned conventional sputtering apparatus, the existing film forming method can adjust the process parameters less, and the adjustment window of the film stress is small, and high compactness cannot be simultaneously achieved under the premise of ensuring process stability and process cost. , more stressful film deposition.

The technical problem to be solved by the present invention is to provide a film forming method for forming a film of high-density tensile stress based on a sputtering process to meet a more advanced integrated circuit process in view of the above-mentioned deficiencies in the prior art.

To achieve the object of the present invention, a film forming method is provided, comprising: looping a first sputtering stage and a second sputtering stage until the thickness of the film satisfies a setting requirement; wherein, in the first sputtering stage and the In the two sputtering stage, pulsed DC power is applied to the target; and, by setting the duty ratio of the pulsed DC power used in the first sputtering stage and the pulsed DC power used in the second sputtering stage, respectively Air ratio to increase the density and stress of the film.

Optionally, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power and RF power to the target; in the second sputtering stage, stopping Apply RF power to the target or continue to apply pulsed DC power and RF power to the target simultaneously.

Optionally, the stress of the film is adjusted by separately adjusting the magnitude of the pulsed DC power used in the first sputtering stage and the magnitude of the pulsed DC power used in the second sputtering stage.

Optionally, in the first sputtering stage, the film stress is adjusted by adjusting the magnitude of the RF power.

Optionally, in the first sputtering stage and/or the second sputtering stage, the bias power is applied to the wafer; by adjusting during the performing the first sputtering stage and/or the second sputtering stage The magnitude of the bias power to adjust the film stress; or, by adjusting the magnitude of the bias power, and maintaining the magnitude of the bias power constant during the first sputtering phase and/or the second sputtering phase Adjust the film stress.

Optionally, adjusting the film pressure by adjusting the process air pressure during the first sputtering phase and/or the second sputtering phase; or, by adjusting the process air pressure, and at the first The film pressure is maintained constant during the sputtering phase and/or the second sputtering phase to adjust the film stress.

Optionally, the duty ratio of the pulsed DC power used in the first sputtering stage is 40% to 80%; and the duty ratio of the pulsed DC power used in the second sputtering stage is 0% to 20%.

Optionally, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power and RF power to the target; in the second sputtering stage, When the application of the RF power to the target is stopped, the duty ratio of the pulsed DC power used in the first sputtering stage is 0%, and the duty ratio of the pulsed DC power used in the second sputtering stage is 40% to 80. %.

Optionally, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power and RF power to the target; in the second sputtering stage, When the pulsed DC power and the RF power are continuously applied to the target, the duty ratio of the pulsed DC power used in the first sputtering stage is 0%, and the duty ratio of the pulsed DC power used in the second sputtering stage It is 0%.

Optionally, when pulsed DC power is applied to the target only in the first sputtering stage and the second sputtering stage, the pulsed DC power used in the first sputtering stage is 5 kW to 10 kW; The pulsed DC power used in the second sputtering stage is 5 kW to 10 kW.

Optionally, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power and RF power to the target; in the second sputtering stage, When the application of the RF power to the target is stopped or the pulsed DC power and the RF power are continuously applied to the target, the pulsed DC power used in the first sputtering stage is 1 kW to 6 kW; the second sputtering stage adopts the The pulsed DC power is from 1 kW to 6 kW.

Optionally, the RF power is from 1 kW to 3 kW.

Optionally, the frequency of the RF power is 13.56 MHz, 27 MHz, 40 MHz or 60 MHz.

Optionally, the time of the first sputtering stage is 5 s to 10 s; and the time of the second sputtering stage is 5 s to 10 s.

Optionally, the bias power is from 0 kW to 2 kW.

Optionally, the first sputtering step and the second sputtering phase are performed in the loop, and before the step of the thickness of the film meeting the setting requirement, the preheating step further comprises: introducing into the reaction chamber The first gas until the process gas pressure reaches the first set pressure; the wafer is heated until the set temperature is reached.

Optionally, the first set air pressure is 1 Torr to 2 Torr; and the set temperature is 300 ° C to 400 ° C.

Optionally, the first sputtering step and the second sputtering phase are performed in the loop until the thickness of the film meets the setting requirement, and after the preheating step, the pressure control step is further included. The method comprises: pumping the reaction chamber; At the same time, the second gas and the third gas are introduced into the reaction chamber, and the gas flow rate of the second gas and the third gas is controlled to keep the process gas pressure constant when the second set pressure is reached.

Optionally, in the first sputtering stage and/or the second sputtering stage, the process gas pressure and the stress of the film are adjusted by adjusting a gas flow ratio of the second gas and the third gas.

Optionally, the first gas is argon; the second gas and the third gas are argon and nitrogen, respectively.

Optionally, the second set air pressure is 10 mTorr to 200 mTorr.

The invention has the beneficial effects that the film forming method provided by the invention has two stages of performing the sputtering process, and applies pulsed direct current to the target in the first sputtering stage and the second sputtering stage. power. Moreover, the density and stress of the film are increased by setting the duty ratio of the pulsed DC power used in the first sputtering stage and the duty ratio of the pulsed DC power used in the second sputtering stage, respectively. Thus, by arranging the duty ratios of the respective pulsed DC powers in two stages, the sputtering energy can be increased without increasing the deposition rate of the film, and increasing the sputtering energy can increase the density of the film, and appropriately reduce it. The deposition rate of the film can prolong the film processing time, increase the production stability, and obtain a film with higher stress. Therefore, the film forming method provided by the invention can simultaneously realize high-density and more stress film deposition under the premise of ensuring process stability and process cost, so as to meet the demanding requirements of the advanced integrated circuit process for film performance. At the same time, the cost of the more advanced process and the difficulty of the process scheme can be reduced, and the invention is especially suitable for the preparation of the high-density TiN film of the 14nm Hardmask process.

In order to enable those skilled in the art to better understand the technical solutions of the present invention, the film forming method provided by the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

Figure 1 is a film forming apparatus used in an embodiment of the present invention. Referring to FIG. 1, the film forming apparatus includes a reaction chamber 1 in which a target 2 is disposed at the top of the reaction chamber 1, and a susceptor 3 for carrying a wafer is disposed under the target 2. The film forming apparatus further includes a radio frequency power source 4, a direct current power source 5, a matcher 6, a bias power source 7, and a capacitance adjusting device 8. Wherein, the RF power source 4 and the DC power source 5 are electrically connected to the target 2 via the matching device 6, so that the RF power source 4 and the DC power source 5 can be avoided compared with the RF power source 4 and the DC power source 5 being separately connected to the target material. The problem of sparking caused by poor matching.

In the present embodiment, the susceptor 3 can be selectively electrically coupled to a bias power source 7 and/or a capacitance adjusting device 8 for applying a negative bias voltage to the susceptor 3 and the wafer thereon. The capacitance adjusting device 8 is capable of adjusting the particle energy of the wafer surface and the thickness of the plasma sheath, thereby improving the stress and density of the film. First embodiment

Referring to FIG. 2, a film forming method according to a first embodiment of the present invention includes: performing a first sputtering stage and a second sputtering stage in a loop until the thickness of the film satisfies a setting requirement.

Wherein, in the first sputtering stage and the second sputtering stage, pulsed DC power is applied to the target. Further, the density and stress of the film are increased by setting the duty ratio A% of the pulsed direct current power used in the first sputtering stage and the duty ratio B% of the pulsed direct current power used in the second sputtering stage, respectively.

The duty ratio of the pulsed DC power is different, and the deposition rate of the film is also different. Under normal conditions, the higher the deposition rate, the higher the deposition stress tends to the compressive stress (the larger the negative value), and the lower the deposition rate, the higher the stress tendency Tensile stress (the positive direction is larger, 0 means no stress, negative is compressive stress, positive value is tensile stress). Based on this, by setting the duty ratio of the pulsed DC power used in the first sputtering stage and the duty ratio of the pulsed DC power used in the second sputtering stage, respectively, the sputtering energy can be increased while appropriately reducing the deposition rate of the film. In order to balance the deposition rate and the sputtering energy, increasing the sputtering energy can increase the compactness of the film, and appropriately reducing the deposition rate of the film can prolong the film processing time, increase the production stability, and obtain a film with higher stress.

Therefore, the film forming method provided by the embodiment can realize high-density and more stress film deposition under the premise of ensuring process stability and process cost, so as to meet the demanding performance of the advanced integrated circuit process. Demand, while reducing the cost of more advanced processes and the difficulty of the process, especially for the preparation of high-density TiN films in the 14nm Hardmask process.

Optionally, the duty ratio A% of the pulsed DC power used in the first sputtering stage is 40% to 80%; and the duty ratio B% of the pulsed DC power used in the second sputtering stage is 0% to 20%.

Optionally, the stress of the film can be adjusted by separately adjusting the magnitude of the pulsed DC power used in the first sputtering stage and the magnitude of the pulsed DC power used in the second sputtering stage. Preferably, the pulsed DC power used in the first sputtering stage is 5 kW to 10 kW; and the pulsed DC power used in the second sputtering stage is 5 kW to 10 kW.

Optionally, the DC power source applies a certain pulsed DC power to the target to achieve plasma ignition. When starting, the duty cycle of the pulsed DC power can be 40% to 80%. In the first sputtering stage, the duty ratio of the pulsed DC power is 40% to 80%; the time of the first sputtering stage is 5s to 10s. In the second sputtering stage, the duty ratio of the pulsed DC power is 0% to 20%; the time of the second sputtering stage is 5s to 10s.

Optionally, bias power is applied to the wafer during the first sputtering phase and/or the second sputtering phase. Also, during the first sputtering phase and/or the second sputtering phase, the film stress is adjusted by adjusting the magnitude of the bias power. Adjusting the bias power allows for a small fine-tuning of the density and stress of the film, which improves the adjustment accuracy. Preferably, the bias power is from 0 kW to 2 kW.

It should be noted that, in practical applications, the bias power can also be maintained at a set value during the sputtering process. Specifically, by adjusting the magnitude of the bias power and maintaining the magnitude of the bias power constant during the first sputtering phase and/or the second sputtering phase, the same can be achieved for adjusting the film stress.

Optionally, the film stress is adjusted by adjusting the process gas pressure during the first sputtering phase and/or the second sputtering phase. Adjusting the process air pressure also adjusts the density and stress of the film. The process gas pressure is the pressure of the reaction chamber. Of course, in practical applications, the film stress can also be adjusted by adjusting the process gas pressure and keeping the process gas pressure constant during the first sputtering phase and/or the second sputtering phase.

Optionally, before the step of performing the first sputtering phase and the second sputtering phase on the loop until the thickness of the film meets the setting requirement, the preheating step further comprises: introducing into the reaction chamber The first gas until the process gas pressure reaches the first set pressure; the wafer is heated until the set temperature is reached.

Optionally, the first gas may be argon; the first set pressure is 1 Torr to 2 Torr; the heating temperature is 300 ° C to 400 ° C; and the heating time is 1 min.

In the preheating step, after the wafer is introduced into the reaction chamber, argon gas is introduced into the reaction chamber until the process gas pressure reaches the first set pressure (1 Torr to 2 Torr). Then, the susceptor temperature was set to 300 ° C to 400 ° C, and the susceptor was heated to the wafer for about 1 min.

Of course, the preheating step can also be completed in the preheating chamber of the film forming apparatus. After the preheating is completed, the wafer reaching the preset temperature is directly introduced into the reaction chamber.

Optionally, after the pre-heating step, further comprising a pressure control step, the pressure control step includes: pumping the reaction chamber; and simultaneously introducing a second gas and a third gas into the reaction chamber, and passing the control The gas flow rates of the two gases and the third gas are such that the process gas pressure remains constant as the second set pressure is reached.

Optionally, in the first sputtering stage and/or the second sputtering stage, the process gas pressure and the stress of the film are adjusted by adjusting the gas flow ratio of the second gas and the third gas.

Optionally, the second gas and the third gas are argon and nitrogen, respectively; and the second set pressure is 10 mTorr to 200 mTorr.

Second embodiment

Referring to FIG. 3, a film forming method according to a second embodiment of the present invention is different from the first embodiment described above in that different sputtering methods, that is, pulsed DC power + RF power are used. Sputtering.

Specifically, the film forming method provided by the second embodiment of the present invention comprises: performing a first sputtering phase and a second sputtering phase in a loop until the thickness of the film satisfies the setting requirement.

Wherein, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, the pulsed DC power and the RF power are simultaneously applied to the target. In the second sputtering stage, the application of radio frequency power to the target is stopped.

Similar to the first embodiment described above, the duty ratio C% of the pulsed DC power used in the first sputtering stage and the duty ratio D% of the pulsed DC power used in the second sputtering stage are respectively set to improve the film. Density and stress.

Optionally, in order to achieve matching of the pulsed DC power and the high frequency RF power, in the first sputtering stage, the duty ratio C% of the pulsed DC power is 0%; the time of the first sputtering stage is 5s to 10s. The duty cycle D% of the pulsed DC power used in the second sputtering stage is 40% to 80%; the time of the second sputtering stage is 5s to 10s.

Optionally, the stress of the film can be adjusted by separately adjusting the magnitude of the pulsed DC power used in the first sputtering stage and the magnitude of the pulsed DC power used in the second sputtering stage. Preferably, the pulsed DC power used in the first sputtering stage is 1 kW to 6 kW; and the pulsed DC power used in the second sputtering stage is 1 kW to 6 kW.

Optionally, the RF power is from 1 kW to 3 kW. The frequency of the RF power is 13.56 MHz, 27 MHz, 40 MHz or 60 MHz.

Similar to the first embodiment described above, the bias power is applied to the wafer during the first sputtering phase and/or the second sputtering phase. Also, during the sputtering process, the film stress is adjusted by adjusting the magnitude of the bias power. Alternatively, the bias power can be maintained at the set value during the sputtering process.

Similar to the first embodiment described above, the film stress is adjusted by adjusting the magnitude of the process gas pressure during the first sputtering phase and/or the second sputtering phase. Alternatively, the film stress can be adjusted by adjusting the process gas pressure and maintaining a constant process gas pressure during the first sputtering phase and/or the second sputtering phase.

Similar to the first embodiment described above, the first sputtering step and the second sputtering phase are performed in the above-described loop, and the preheating step is included until the thickness of the film satisfies the setting requirement. The preheating step has been described in detail in the above first embodiment, and will not be described herein.

Optionally, after the preheating step, a pressure control step is further included. The pressure control step has been described in detail in the above first embodiment, and details are not described herein again. Third embodiment

Referring to FIG. 4, a film forming method according to a third embodiment of the present invention is different from the second embodiment described above in that both the first sputtering stage and the second sputtering stage simultaneously apply a pulse to the target. DC power and RF power.

Specifically, the film forming method provided by the third embodiment of the present invention comprises: performing a first sputtering phase and a second sputtering phase in a loop until the thickness of the film satisfies the setting requirement.

Wherein, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, the pulsed DC power and the RF power are simultaneously applied to the target. In the second sputtering stage, simultaneous application of pulsed DC power and RF power to the target is continued.

Similar to the second embodiment described above, the duty ratio E% of the pulsed DC power used in the first sputtering stage and the duty ratio F% of the pulsed DC power used in the second sputtering stage are respectively set to improve the film. Density and stress.

Optionally, in order to achieve matching between the pulsed DC power and the high frequency RF power, the duty ratio E% of the pulsed DC power used in the first sputtering stage is 0%, and the duty of the pulsed DC power used in the second sputtering stage is occupied. The ratio F% is 0%.

Optionally, the stress of the film can be adjusted by separately adjusting the magnitude of the pulsed DC power used in the first sputtering stage and the magnitude of the pulsed DC power used in the second sputtering stage. Preferably, the pulsed DC power used in the first sputtering stage is 1 kW to 6 kW; and the pulsed DC power used in the second sputtering stage is 1 kW to 6 kW.

Optionally, the RF power is from 1 kW to 3 kW. The frequency of the RF power is 13.56 MHz, 27 MHz, 40 MHz or 60 MHz.

Similar to the first and second embodiments described above, the bias power is applied to the wafer during the first sputtering phase and/or the second sputtering phase. Also, during the sputtering process, the film stress is adjusted by adjusting the magnitude of the bias power. Alternatively, the bias power can be maintained at the set value during the sputtering process.

Similar to the first and second embodiments described above, the film stress is adjusted by adjusting the magnitude of the process gas pressure in the first sputtering stage and/or the second sputtering stage. Alternatively, the film stress can be adjusted by adjusting the process gas pressure and maintaining a constant process gas pressure during the first sputtering phase and/or the second sputtering phase.

Similar to the first and second embodiments described above, the first sputtering step and the second sputtering phase are performed in the above-described loop, and the preheating step is further included until the thickness of the film satisfies the setting requirement. The preheating step has been described in detail in the above first and second embodiments, and details are not described herein again.

Optionally, after the preheating step, a pressure control step is further included. The pressure control step has been described in detail in the above first and second embodiments, and details are not described herein again.

The film data obtained by the film forming methods provided in the first to third embodiments are compared with those obtained by the film forming method in the prior art.

Table 1, process parameters and film data for the film forming methods provided in the first to third embodiments, and process parameters and film data of the film forming method in the prior art.

As can be seen from the above Table 1, the prior art film forming method employs a single step sputtering method and applies pulsed DC power to the target. The film obtained by this method has a density of 4.5 to 4.9 g/cc, and the density is low. At the same time, the stress of the film is <0, which is a compressive stress, and cannot be adapted to a more advanced integrated circuit process. In contrast, the film obtained by the film forming method provided by the first to third embodiments of the present invention has a density of more than 5.0 g/cc, and a hard mask having a tensile stress of 100 to 1000 MPa can be obtained. Therefore, it is possible to simultaneously achieve high-density and more stress film deposition under the premise of ensuring process stability and process cost, so as to meet the demanding requirements of the advanced integrated circuit process for film performance.

It is to be understood that the above embodiments are merely exemplary embodiments employed to explain the principles of the invention, but the invention is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and scope of the invention. These modifications and improvements are also considered to be within the scope of the invention.

1‧‧‧reaction chamber

2‧‧‧ Target

3‧‧‧Base

4‧‧‧RF power supply

5‧‧‧DC power supply

6‧‧‧matcher

7‧‧‧ bias power supply

8‧‧‧Capacitor adjustment device

1 is a flow chart of a film forming apparatus according to an embodiment of the present invention; FIG. 2 is a flow chart of a film forming method according to a first embodiment of the present invention; 4 is a flow chart of a film forming method according to a third embodiment of the present invention.

Claims (21)

A film forming method, comprising: performing a first sputtering stage and a second sputtering stage in a loop until the thickness of the film satisfies a setting requirement; wherein, in the first sputtering stage and the second sputtering In the plating stage, a pulse of DC power is applied to the target; and, by setting the duty ratio of the pulsed DC power used in the first sputtering stage and the duty of the pulsed DC power used in the second sputtering stage, respectively To increase the density and stress of the film. The film forming method according to claim 1, wherein in the first sputtering stage, after applying a radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power to the target and RF power; during this second sputtering phase, the application of RF power to the target is stopped or pulsed DC power and RF power are continuously applied to the target. The film forming method according to claim 1 or 2, wherein the magnitude of the pulsed DC power used in the first sputtering stage and the pulsed DC power used in the second sputtering stage are separately adjusted. The size of the film to adjust the stress. The film forming method according to claim 2, wherein in the first sputtering stage, the film stress is adjusted by adjusting the magnitude of the RF power. The film forming method according to claim 1 or 2, wherein in the first sputtering stage and/or the second sputtering stage, a bias power is applied to the wafer; Adjusting the bias power during the first sputtering phase and/or the second sputtering phase to adjust the film stress; or, by adjusting the magnitude of the bias power, and during the first sputtering phase and/or Or maintaining the magnitude of the bias power constant during the second sputtering phase to adjust the film stress. The film forming method according to claim 1 or 2, wherein the film is adjusted by adjusting a process gas pressure during the first sputtering phase and/or the second sputtering phase. Stress; or, by adjusting the magnitude of the process gas pressure and maintaining a constant magnitude of the process gas pressure during the first sputtering phase and/or the second sputtering phase, the film stress is adjusted. The film forming method of claim 1, wherein the duty ratio of the pulsed DC power used in the first sputtering stage is 40% to 80%; the pulsed direct current used in the second sputtering stage The duty cycle of the power is 0% to 20%. The film forming method of claim 2, wherein, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power to the target and RF power; in the second sputtering stage, when the application of the RF power to the target is stopped, the duty ratio of the pulsed DC power used in the first sputtering stage is 0%, and the second sputtering stage adopts the The duty cycle of the pulsed DC power is 40% to 80%. The film forming method of claim 2, wherein, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power to the target and RF power; in the second sputtering stage, when pulsed DC power and RF power are simultaneously applied to the target, the duty ratio of the pulsed DC power used in the first sputtering stage is 0%, and the second splash The duty cycle of the pulsed DC power used in the plating phase is 0%. The film forming method of claim 3, wherein, in the first sputtering stage and the second sputtering stage, when the pulsed direct current power is applied only to the target, the first sputtering stage is used. The pulsed DC power is 5 kW to 10 kW; the pulsed DC power used in the second sputtering phase is 5 kW to 10 kW. The film forming method of claim 3, wherein, in the first sputtering stage, after applying radio frequency power to the target to achieve plasma ignition, simultaneously applying pulsed DC power to the target and RF power; in the second sputtering stage, when the application of the RF power to the target is stopped or the pulsed DC power and the RF power are continuously applied to the target, the DC power of the pulse used in the first sputtering stage is 1 kW. ～6 kW; the pulsed DC power used in the second sputtering stage is 1 kW to 6 kW. The film forming method according to claim 4, wherein the RF power has a size of 1 kW to 3 kW. The film forming method according to claim 2, wherein the frequency of the radio frequency power is 13.56 MHz, 27 MHz, 40 MHz or 60 MHz. The film forming method according to claim 1 or 2, wherein the time of the first sputtering stage is 5 s to 10 s; and the time of the second sputtering stage is 5 s to 10 s. The film forming method according to claim 5, wherein the bias power is from 0 kW to 2 kW. The film forming method according to claim 1, wherein the first sputtering stage and the second sputtering stage are performed in the loop until a step of the thickness of the film satisfies the setting requirement, and a preheating step is further included. The preheating step includes: introducing a first gas into a reaction chamber until the process gas pressure reaches a first set pressure; and heating the wafer until a set temperature is reached. The film forming method according to claim 16, wherein the first set gas pressure is 1 Torr to 2 Torr; and the set temperature is 300 ° C to 400 ° C. The film forming method of claim 16, wherein the loop is subjected to a first sputtering stage and a second sputtering stage until the thickness of the film satisfies the setting requirement, and the After the heating step, further comprising a pressure control step, the pressure control step includes: pumping the reaction chamber; simultaneously introducing a second gas and a third gas into the reaction chamber, and controlling the second The gas flow rate of the gas and the third gas is such that the process gas pressure remains constant until a second set pressure is reached. The film forming method according to claim 18, wherein in the first sputtering stage and/or the second sputtering stage, the gas flow ratio of the second gas and the third gas is adjusted to adjust Process pressure and film stress. The film forming method according to claim 18, wherein the first gas is argon gas; and the second gas and the third gas are argon gas and nitrogen gas, respectively. The film forming method according to claim 18, wherein the second set pressure is 10 mTorr to 200 mTorr.