阅读说明：本技术 制膜方法 (Film forming method ) 是由 张同文 罗建恒 耿波 武学伟 于 2018-08-14 设计创作，主要内容包括：本发明提供一种制膜方法,其包括：第一溅射阶段,向靶材加载射频功率,以在晶片表面上形成保护层；第二溅射阶段,同时向靶材加载射频功率和直流功率,以在保护层上形成薄膜。本发明提供的制膜方法,其可以减少对晶片表面造成损伤,从而可以提高产品性能。(The present invention provides a film-making method comprising: a first sputtering stage, loading radio frequency power to a target material to form a protective layer on the surface of a wafer; and in the second sputtering stage, the target is loaded with radio frequency power and direct current power at the same time so as to form a film on the protective layer. The film preparation method provided by the invention can reduce damage to the surface of the wafer, thereby improving the product performance.)

1. A method of making a film, comprising:

a first sputtering stage, loading radio frequency power to a target material to form a protective layer on the surface of a wafer;

and in the second sputtering stage, simultaneously loading radio frequency power and direct current power to the target to form a film on the protective layer.

2. The method of manufacturing a film according to claim 1, wherein the first sputtering step includes the steps of:

s1, introducing process gas into the reaction chamber until the process gas pressure reaches a first preset value and keeping the process gas pressure at the first preset value; the flow rate of the process gas is a first flow rate value;

s2, loading radio frequency power to the target material to start plasma;

s3, keeping applying the radio frequency power to the target material to form the protective layer on the surface of the wafer.

3. The film forming method according to claim 2, further comprising, after step S2:

and reducing the process pressure to a second pressure value.

4. The film forming method according to claim 2, further comprising, after step S2:

reducing the flow of the process gas to a second flow value.

5. The method of manufacturing a film according to claim 2, wherein the second sputtering step includes the steps of:

s4, keeping loading radio frequency power to the target, increasing the flow of the process gas to a third flow value, and loading direct current power to the target;

s5, reducing the flow of the process gas to a fourth flow value, and simultaneously keeping applying radio frequency power and direct current power to the target so as to form the film on the protective layer.

6. The method of any one of claims 1 to 5, wherein the radio frequency power has a value in a range of 50W to 1000W.

7. The method of manufacturing a film according to any one of claims 1 to 5, wherein the dc power is set to a value in a range of 10W to 1000W.

8. The method for forming a film according to any one of claims 2 to 5, wherein a flow rate of the process gas is in a range of 10sccm to 200 sccm.

9. The method of manufacturing a film according to any one of claims 1 to 5, wherein a thickness of the protective layer is in a range of 10A to 1000A.

10. The film-forming method according to any one of claims 1 to 5, wherein a thickness of the film is in a range of 300A to 20000A.

Technical Field

The invention relates to the field of film manufacturing, in particular to a film manufacturing method.

Background

In recent years, due to the huge market demand of Light Emitting Diodes (LEDs), GaN-based LEDs are widely used in different fields such as high-power illumination lamps, automobile instrument displays, large-area outdoor display screens, signal lamps, and general illumination. In the manufacturing process of the LED chip, the low doping of the P-type GaN and the low light transmittance of the P-type ohmic metal contact cause higher contact resistance and low light transmittance, and the improvement of the overall performance of the LED chip is seriously influenced. In order to improve the light extraction efficiency and reduce the contact resistance, the research of developing the transparent conductive film suitable for the P-type GaN is very important. Compared with the traditional metal film, the ITO film as a transparent conductive film has the advantages of high visible light transmittance, good conductivity, abrasion resistance, corrosion resistance and the like, and the ITO film and the GaN have good adhesion. Therefore, the ITO thin film is widely used as an electrode material for GaN-based chips.

There are many methods for preparing ITO thin films, such as spraying, chemical vapor deposition, evaporation coating, magnetron sputtering, etc. Among these methods, the ITO thin film prepared by the magnetron sputtering method has a low resistivity, a high visible light transmittance, and a high reproducibility. The existing preparation method of the ITO film comprises the following steps: introducing process gas (such as Ar) into the reaction chamber, loading radio frequency power to the target material to excite the process gas to form plasma, then loading direct current power to the target material while continuously loading the radio frequency power to the target material, and bombarding the target material by the plasma under the traction of an electric field to enable the target material to be sputtered onto the surface of the wafer, thereby forming the ITO film.

However, since the above film-forming method uses Radio Frequency (RF) and Direct Current (DC) co-sputtering, energy of a target material sputtered from a target is large, and when the target material is sputtered onto a wafer surface, GaN on the wafer is damaged, which causes an increase in VF (forward voltage) value and a decrease in Iv (light emission intensity) value of a product, thereby resulting in a decrease in product performance.

Disclosure of Invention

The invention aims to solve at least one technical problem in the prior art, and provides a film manufacturing method which can reduce damage to the surface of a wafer, so that the product performance can be improved.

To achieve the object of the present invention, there is provided a film-making method comprising:

a first sputtering stage, loading radio frequency power to a target material to form a protective layer on the surface of a wafer;

and in the second sputtering stage, simultaneously loading radio frequency power and direct current power to the target to form a film on the protective layer.

Optionally, the first sputtering stage includes the following steps:

s1, introducing process gas into the reaction chamber until the process gas pressure reaches a first preset value and keeping the process gas pressure at the first preset value; the flow rate of the process gas is a first flow rate value;

s2, loading radio frequency power to the target material to start plasma;

s3, keeping applying the radio frequency power to the target material to form the protective layer on the surface of the wafer.

Optionally, after the step S2, the method further includes:

and reducing the process pressure to a second pressure value.

Optionally, after the step S2, the method further includes:

reducing the flow of the process gas to a second flow value.

Optionally, the second sputtering stage includes the following steps:

s4, keeping loading radio frequency power to the target, increasing the flow of the process gas to a third flow value, and loading direct current power to the target;

s5, reducing the flow of the process gas to a fourth flow value, and simultaneously keeping applying radio frequency power and direct current power to the target so as to form the film on the protective layer.

Optionally, the value range of the radio frequency power is 50W-1000W.

Optionally, the value range of the dc power is 10W to 1000W.

Optionally, the flow rate of the process gas ranges from 10sccm to 200 sccm.

The thickness of the optional protective layer ranges from 10A to 1000A.

Optionally, the thickness of the thin film ranges from 300A to 20000A.

The invention has the following beneficial effects:

the film preparation method provided by the invention divides the sputtering process into two stages, wherein, the first sputtering stage loads radio frequency power to the target material to form a protective layer on the surface of a wafer; and the second sputtering stage simultaneously loads radio frequency power and direct current power to the target material to form a film on the protective layer. Because only the radio frequency power is loaded to the target material in the first sputtering stage, the radio frequency power can generate larger negative bias on the target material to sufficiently attract plasma to bombard the target material, meanwhile, the energy of the sputtered target material is smaller, the sputtered target material causes less damage to the surface of the wafer when being sputtered onto the surface of the wafer, and even has no loss, and finally, a thin film is formed on the surface of the wafer to be used as a protective layer. The second sputtering stage loads radio frequency power and direct current power to the target simultaneously, so that the energy of the sputtered target material is larger, a very compact film can be formed on the surface of the wafer, and meanwhile, by means of the protective layer, the surface of the wafer cannot be damaged even if the energy of the material is larger, and the product performance can be improved.

Drawings

FIG. 1 is a flow chart of a film-making method provided by the present invention;

fig. 2 is a flowchart of a first sputtering stage of a film forming method according to an embodiment of the present invention;

fig. 3 is a flowchart of a second sputtering stage of the film forming method according to the embodiment of the present invention.

Detailed Description

In order to make those skilled in the art better understand the technical solution of the present invention, the following describes the film-forming method provided by the present invention in detail with reference to the accompanying drawings.

Referring to fig. 1, the film forming method provided by the present invention includes:

a first sputtering stage, loading radio frequency power to a target material to form a protective layer on the surface of a wafer;

and in the second sputtering stage, the target is loaded with radio frequency power and direct current power at the same time so as to form a film on the protective layer.

Because only the radio frequency power is loaded to the target material in the first sputtering stage, the radio frequency power can generate larger negative bias on the target material to sufficiently attract plasma to bombard the target material, meanwhile, the energy of the sputtered target material is smaller, the sputtered target material causes less damage to the surface of the wafer when being sputtered onto the surface of the wafer, and even has no loss, and finally, a thin film is formed on the surface of the wafer to be used as a protective layer. The second sputtering stage loads radio frequency power and direct current power to the target simultaneously, so that the energy of the sputtered target material is larger, a very compact film can be formed on the surface of the wafer, and meanwhile, by means of the protective layer, the surface of the wafer cannot be damaged even if the energy of the material is larger, and the product performance can be improved.

The film preparation method provided by the invention can be applied to the preparation of electrode materials of GaN-based chips, such as the preparation of ITO films, and can reduce the damage to GaN on wafers. Of course, the method can also be applied to the preparation of films on the surfaces of other easily damaged substrates.

Optionally, referring to fig. 2, the first sputtering stage includes the following steps:

s1, introducing process gas into the reaction chamber until the process gas pressure reaches a first preset value and keeping the process gas pressure at the first preset value; the flow rate of the process gas is a first flow rate value;

s2, loading radio frequency power to the target material to start plasma;

and S3, keeping applying the radio frequency power to the target to form a protective layer on the surface of the wafer.

The gas pressure in the chamber can be stabilized by the above step S1. The first preset value can be freely set according to specific process requirements, and preferably, an exhaust valve of the reaction chamber can be adjusted to be in a half-open state, so that the air pressure in the chamber is kept in a higher value range, and the radio frequency power can be normally loaded.

Optionally, in the step S1, the flow rate of the process gas (i.e., the first flow rate value) ranges from 10sccm to 200sccm, and preferably, the first flow rate value is 150 sccm.

In step S2, the process gas pressure is maintained at the first preset value while the rf power is applied to the target. Optionally, the value range of the radio frequency power is 50W to 1000W, preferably 250W.

Optionally, after step S2, the method further includes:

and reducing the process pressure to a second pressure value.

By reducing the process gas pressure, it is beneficial to form a protective layer on the wafer surface.

Alternatively, the reduction of the second air pressure value may adjust an exhaust valve of the reaction chamber to a fully open state.

Optionally, in the step S3, the value of the rf power ranges from 50W to 1000W, preferably 250W. The thickness of the protective layer ranges from 10A to 1000A, preferably 100A.

Optionally, after the step S2, the method further includes:

the flow of the process gas is reduced to a second flow value.

By reducing the flow of process gas, it is beneficial to form a protective layer on the wafer surface. Optionally, the second flow value is 35 sccm.

Referring to fig. 3, the second sputtering stage includes the following steps:

s4, keeping loading radio frequency power to the target, increasing the flow of the process gas to a third flow value, and loading direct current power to the target;

s5, reducing the flow of the process gas to a fourth flow value while maintaining the RF power and the DC power applied to the target to form a film on the protective layer.

Optionally, the third flow rate is 120 sccm.

Optionally, the fourth flow value is 60 sccm.

Optionally, the value range of the dc power is 10W to 1000W, preferably 260W.

Optionally, the thickness of the film ranges from 300A to 20000A, preferably 500A.

The product performance obtained by the film-making method provided by the invention is compared with the product performance obtained by the film-making method in the prior art.

Table 1 shows the product parameters obtained by the film-forming method of the present invention and the product parameters obtained by the film-forming method of the prior art.

In the above Table 1, V_FRepresenting the forward voltage, refers to the voltage drop across the device in volts (V) at the rated forward current. I is_vRepresentative of luminous intensity, refers to the luminous flux emitted per unit solid angle in a given direction, in candelas (cd).

As can be seen from Table 1, V of the product obtained by the film-forming method of the present invention_FHas an average value of 3.38V, I_vHas an average value of 84.9 cd. V of the product obtained by the film-making method of the prior art_FHas an average value of 3.49V, I_vHas an average value of 82.88 cd. In contrast, V can be obtained by the film-forming method provided by the present invention_FLower value, I_vHigher value products, thereby improving the product performance.

It will be understood that the above embodiments are merely exemplary embodiments taken to illustrate the principles of the present invention, which is not limited thereto. It will be apparent to those skilled in the art that various modifications and improvements can be made without departing from the spirit and substance of the invention, and these modifications and improvements are also considered to be within the scope of the invention.