KR20140067905A - Plasma processing apparatus and plasma processing method - Google Patents

Abstract

A plasma processing apparatus of the present invention is provided to perform uniform plasma processing by reducing the reactivity of the surrounding of a substrate which is subject to be processed without using rectifying wall or sacrificial member which consumes much radical. The plasma processing apparatus of the present invention includes a processing container (2) for performing plasma processing by accepting a substrate G; a substrate mount table (4) for mounting the substrate G in the processing container (2); process gas supply units (20, 28) for supplying a process gas into the processing container; a discharge unit (30) for discharging gas inside the processing container (2); a high-frequency power source (14a) which is a plasma source for generating plasma of the process gas in the processing container (2); and trap gas supply units (16, 19) for supplying trap gas for trapping active species in the plasma in the surrounding of the substrate G on the substrate mount table (4).

Description

TECHNICAL FIELD [0001] The present invention relates to a plasma processing apparatus and a plasma processing method.

TECHNICAL FIELD [0001] The present invention relates to a plasma processing apparatus and a plasma processing method for performing plasma processing such as plasma etching.

2. Description of the Related Art Plasma processing such as etching, sputtering, and CVD (Chemical Vapor Deposition) has been used extensively in a manufacturing process of a flat panel display (FPD) or a semiconductor device.

For example, in the case of performing plasma etching as a plasma treatment, the treatment gas is dissociated into a plasma, and the generated active species such as radicals react with the film to be etched.

In the case where the film to be etched has a high chemical reactivity, the etching rate at the peripheral portion of the substrate to be processed tends to increase due to the influence of loading, which often limits the uniformity of etching.

As a technique for suppressing the tendency of the etching rate to increase at such a peripheral edge portion, it is known to arrange rectifying walls which are vertical side walls so as to surround the substrate to be processed to suppress the flow of the processing gas at the periphery of the substrate to be processed For example, Patent Document 1). It is also conceivable to arrange a member having a large amount of radical consumption as described in Patent Document 2 as a sacrificial material on the outer region of the substrate to be processed to reduce the influence of loading.

(Prior art document)

(Patent Literature)

(Patent Document 1) Japanese Unexamined Patent Application Publication No. 2003-243364

(Patent Document 2) JP-A-5-190502

However, in the case of using the rectifying wall, it is necessary to optimize the rectifying wall in accordance with the type of the film to be etched and the etching condition (recipe), which is troublesome. Further, in the case of using a sacrificial material having a large amount of radical consumption, since the sacrificial material is a consumable item, it is necessary to replace it regularly, which is troublesome and costly. Further, in both of the techniques, when a plurality of etching layers are successively processed, the other etching target films are affected, and a process problem may occur.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a plasma processing apparatus and plasma processing apparatus capable of reducing the reactivity of a peripheral portion of a substrate to be processed and performing uniform plasma processing without using a sacrificial material having a large amount of rectification wall or radical consumption, And to provide an image processing apparatus.

In order to solve the above problems, according to a first aspect of the present invention, there is provided a plasma processing apparatus for performing plasma processing on a substrate, comprising: a processing vessel for receiving a substrate and performing a plasma treatment; An exhaust mechanism for exhausting the inside of the processing vessel; a plasma generating means for generating a plasma of the processing gas in the processing vessel; And a trap gas supply mechanism for supplying a trap gas for trapping active species in the plasma to a peripheral portion of the substrate on the substrate mounting base.

According to a second aspect of the present invention, there is provided a plasma processing method for performing plasma processing on a substrate, comprising the steps of: supplying a processing gas into a processing vessel in a state where a substrate is mounted on a substrate mounting table in the processing vessel; And a trap gas for trapping active species in the plasma is supplied to a peripheral portion of the substrate at the time of the plasma treatment.

In the first and second aspects, the plasma treatment may be a plasma etching treatment. Further, the process gas may be a gas containing at least one of F, Cl, and O, and the trap gas may be a hydrogen gas. Further, the ratio of the number of atoms of the trapping gas to the number of atoms of the active species in the process gas can be set to 17 to 80%.

When the plasma treatment is a plasma etching treatment, the object to be etched may be one of an Si film, an SiN _x film, and an Al film formed on the substrate. In the case where the object to be etched is a Si film, F may be used as the active species, and the ratio of the number of atoms of the trap gas to the number of atoms of the active species in the processing gas may be 40 to 80%. The ratio of the number of atoms of the trap gas to the number of atoms of the active species in the process gas may be 17.1 to 34.3% by using F and O as the active species when the object to be etched is the SiN _x film. Cl may be used as the active species when the object to be etched is an Al film, and the ratio of the number of atoms of the trap gas to the number of atoms of the active species in the process gas may be 40 to 80%.

In the first aspect, the trap gas supply mechanism may be provided around the substrate of the substrate mounting table. The processing gas supply mechanism may include a shower head for supplying the processing gas in a shower shape toward the substrate on the substrate mounting table in the processing vessel, and the trap gas supply mechanism is provided around the shower head It may be.

According to a third aspect of the present invention, there is provided a storage medium storing a program for controlling a plasma processing apparatus, the storage medium being operable on a computer, the program causing the computer to execute a plasma processing method of the second aspect, And controls the plasma processing apparatus.

According to the present invention, at the time of plasma processing, a trap gas for trapping active species in the plasma is supplied to the peripheral portion of the substrate on the substrate mounting table. Therefore, when the plasma processing rate is large at the outer peripheral portion of the substrate, the processing rate of that portion can be lowered and the uniformity of the plasma processing distribution can be increased.

1 is a cross-sectional view showing a plasma etching apparatus as a plasma processing apparatus according to a first embodiment of the present invention.
Fig. 2 is a sectional view partially showing a substrate mounting table in the plasma etching apparatus of Fig. 1. Fig.
3 is a plan view showing a substrate mounting table in the plasma etching apparatus of FIG.
4 is a cross-sectional view showing another example of the trap gas discharge nozzle.
5 is a cross-sectional view showing another example of the trap gas discharge nozzle.
6 is a cross-sectional view showing a plasma etching apparatus as a plasma processing apparatus according to a second embodiment of the present invention.
7 is a schematic diagram for explaining Experimental Example 1. Fig.
8 is a view showing the relationship between the amount of H ₂ gas as a trap gas supplied to the peripheral portion of the substrate and the etching distribution when the a-Si film is plasma-etched.
9 is a view showing the relationship between the amount of H ₂ gas as a trap gas and the etching distribution when the SiN _x film is plasma-etched.
10 is a graph showing the relationship between the supply amount of H ₂ gas as a trap gas to the peripheral portion of the substrate and the etching distribution when the Al film is plasma-etched.
11 is a diagram showing the relationship between the amount of H ₂ gas supplied to the peripheral portion of the substrate when the a-Si film is etched and the emission spectrum of the plasma.
12 is a cross-sectional view showing a stacked structure of an object to be etched when LTPS contact etching is carried out in Experimental Example 2. Fig.
13 is a view showing the etching distribution of the SiO ₂ film depending on the presence or absence of the supply of the H ₂ gas as the trap gas in Experimental Example 2. FIG.
14 is a graph showing the etching distribution of the SiN _x film depending on the presence or absence of supply of the H ₂ gas as the trap gas in Experimental Example 2. FIG.
15 is a graph showing the etching distribution of the a-Si film depending on the presence or absence of supply of the H ₂ gas which is the trap gas in Experimental Example 2. FIG.
16 is a diagram showing the results of Experimental Example 3;

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the present invention, a plasma etching apparatus is described as an example of a plasma processing apparatus.

≪ First Embodiment >

First, the first embodiment will be described.

Fig. 1 is a cross-sectional view showing a plasma etching apparatus as a plasma processing apparatus according to a first embodiment of the present invention, Fig. 2 is a cross- sectional view partially showing a substrate mounting table in the plasma etching apparatus of Fig. 1 is a plan view showing a substrate mounting table in a plasma etching apparatus; Fig.

As shown in Fig. 1, the plasma etching apparatus 1 is configured as a capacitively coupled plasma etching apparatus for etching a glass substrate for an FPD (hereinafter simply referred to as " substrate ") G. Examples of the FPD include a liquid crystal display (LCD), an electro luminescence (EL) display, a plasma display panel (PDP), and the like. The plasma etching apparatus 1 is provided with a chamber 2 as a processing vessel for accommodating a substrate G as a substrate to be processed. The chamber 2 is made of, for example, aluminum whose surface has been subjected to an alumite treatment (anodizing treatment), and is formed in a rectangular parallelepiped shape corresponding to the shape of the substrate G.

On the bottom of the chamber 2, there is provided a substrate mounting table 4 functioning as a lower electrode with an insulating plate 3 made of an insulating material interposed therebetween. The substrate table 4 is made of a metal such as aluminum and has a convex portion 5a formed at the central portion of the upper portion and a plunge 5b around the convex portion 5a, (5), and an insulating member (6) provided on the convex portion (5a) and having a mounting surface of the substrate (G). A planar adsorption electrode 6a is provided inside the insulating member 6, and an electrostatic chuck for electrostatically adsorbing the substrate G is formed. Above the plunger 5b, a shield ring 7 made of a frame-like insulator is provided so as to surround the mounted substrate G. Further, an insulating ring 8 is provided so as to surround the periphery of the substrate 5. [ The insulating member 6, the shield ring 7, and the insulating ring 8 are made of insulating ceramics such as alumina.

A feed line 12 for feeding a high frequency power is connected to the base material 5. This feed line 12 is branched and connected to one branch line by a matching device 13a and a first high frequency The power source 14a is connected, and the matching device 13b and the second high frequency power source 14b for bias application are connected to the other branch line. From the first RF power supply 14a, for example, 13.56 MHz high-frequency power for generating plasma is applied to the substrate 5, whereby the substrate table 4 functions as a lower electrode. From the second high frequency power source 14b, a high frequency power of, for example, 3.2 MHz for bias is applied to the substrate 5, whereby the ions in the plasma can be attracted to the substrate G effectively. It is also possible to provide a single high-frequency power source for both plasma generation and bias application. The direct current power supply 15 is connected to the adsorption electrode 6a so that the direct current voltage is applied to the adsorption electrode 6a and the substrate G is attracted to the mounting surface of the insulating member 6 by the Coulomb force.

On the upper surface of the shield ring 7, a frame shape for discharging hydrogen gas (H ₂ gas) as a trap gas for trapping active species (radicals) in the plasma so as to surround the mounting surface of the substrate G is formed A trap gas discharge nozzle 16 is provided. On the upper surface of the trap gas discharge nozzle 16, a plurality of gas discharge openings 17 are formed over the entire circumference. The trap gas discharge nozzle 16 is connected to a gas flow path 18 and to the other end of the gas flow path 18 is connected a trap gas supply source 19 for supplying hydrogen gas as a trap gas. The hydrogen gas serving as the trap gas is supplied from the trap gas supply source 19 to the trap gas discharge nozzle 16 through the gas flow path 18 and discharged from the plurality of gas discharge ports 17, And is supplied to the peripheral portion of the substrate G above.

The substrate table 4 is provided with a plurality of lifter pins (not shown) for moving the substrate G to and from the upper surface of the substrate table 4 (that is, the upper surface of the insulating member 6) , And the substrate G is transferred to the lifter pin projecting upward from the upper surface of the substrate table 4.

An upper portion of the chamber 2 is provided so as to face the substrate table 4 with a showerhead 20 which supplies a processing gas into the chamber 2 and also functions as an upper electrode. The shower head 20 is provided with a gas diffusion space 21 for diffusing a process gas therein and a plurality of discharge holes 22 for discharging a process gas on a surface opposed to the lower surface or the substrate table 4 Is formed. The showerhead 20 is grounded and constitutes a pair of parallel plate electrodes together with the substrate table 4. [

A gas inlet 24 is provided on the upper surface of the showerhead 20. A process gas supply pipe 25 is connected to the gas inlet 24. The process gas supply pipe 25 is connected to a process gas supply source 28 are connected. In the process gas supply pipe 25, a valve 26 and a mass flow controller 27 are provided. From the process gas supply source 28, a process gas for etching is supplied. As the process gas, a process gas commonly used in this field can be used, and an optimum material is used depending on the film to be processed. As such a process gas, typically, a gas containing at least one of F, Cl, and O can be used. Each of these forms an active species (radical) containing highly reactive F, Cl, O.

An exhaust pipe 29 (only two shown) is connected to four corners of a bottom wall of the chamber 2. An exhaust device 30 is connected to the exhaust pipe 29 and a pressure regulating valve Lt; / RTI > The exhaust device 30 is equipped with a vacuum pump such as a turbo molecular pump, and is configured to evacuate the inside of the chamber 2 and to evacuate it to a predetermined reduced-pressure atmosphere. A gate valve 32 for opening and closing the loading / unloading port 31 is provided on the side wall of the chamber 2 and a loading / unloading port 31 for loading / unloading the substrate G is provided. The substrate G is configured to be carried in and out of the chamber 2 by a transfer means not shown.

The plasma etching apparatus 1 also includes a control unit 40 having a process controller including a microprocessor (computer) for controlling the respective components of the plasma etching apparatus 1. [ The control unit 40 includes a keyboard for performing an input operation such as a command input for managing the plasma etching apparatus 1 by the operator or a user interface including a display for visually displaying the operating state of the plasma etching apparatus 1, A control program for realizing various processes to be executed by the plasma etching apparatus 1 under the control of the process controller, and a storage unit for storing a program for executing a process on each component of the plasma processing apparatus, I have more. The processing recipe is stored in the storage medium in the storage unit. The storage medium may be a hard disk or a semiconductor memory built in a computer, or may have a portability such as a CDROM, a DVD, and a flash memory. Further, the recipe may be appropriately transmitted from another apparatus, for example, through a dedicated line. If necessary, an arbitrary processing recipe is called from the storage unit by an instruction or the like from the user interface and is executed by the process controller, whereby the desired processing in the plasma etching apparatus is performed under the control of the process controller.

Next, the processing operation in the plasma etching apparatus 1 having the above-described structure will be described. The following processing operations are performed under the control of the operation of the control unit 40. [

First, the interior of the chamber 2 is evacuated by the evacuating device 30 to a predetermined pressure, the gate valve 32 is opened, and a transfer chamber (not shown in the figure) (Not shown) to transfer the substrate G thereon in a state in which the lifter pin (not shown) is raised, and the lifter pin is lowered to lift the substrate G from the substrate G is mounted. After the conveying means is retracted from the chamber 2, the gate valve 32 is closed.

In this state, the processing gas is supplied from the processing gas supply source 28 through the processing gas supply pipe 25 and the showerhead 20 into the chamber 2, and the pressure in the chamber 2 is regulated by the pressure regulating valve Adjust it to a predetermined degree of vacuum.

The RF power for plasma generation is applied from the first RF power supply 14a to the substrate table 4 (base material 5) through the matching unit 13a and the substrate table 4 as a lower electrode A high-frequency electric field is generated between the showerhead 20 as the upper electrode, and the process gas in the chamber 2 is made plasma. In addition, high frequency power for bias is applied from the second high frequency power source 14b to the substrate table 4 (base material 5) via the matching unit 13b to effectively attract the ions in the plasma to the substrate G. At this time, by applying a DC voltage to the attracting electrode 6a from the DC power supply 15, the substrate G is attracted to the mounting surface of the substrate mount 4 (insulating member 6) by the Coulomb force through the plasma Adsorption and fixing.

As a result, the plasma etching process for the predetermined film of the substrate G proceeds. At this time, as the process gas, an optimum material is used depending on the film to be processed, and at least one of F, Cl, and O, which generates active species (radicals) containing F, Cl, and O having high reactivity by plasma, A gas containing one species can be used.

When the plasma etching process is performed, unreacted process gas is present at a peripheral portion of the substrate G. Therefore, if the film to be etched has high chemical reactivity, the etching rate at the peripheral portion of the substrate G increases due to the loading effect.

Therefore, in the present embodiment, hydrogen gas is supplied as a trap gas for trapping active species (radicals) in the plasma from a trap gas supply source 19 through a gas flow path 18 to a plurality of gas And supplies it to the peripheral portion of the substrate G from the discharge port 17. As a result, active species (radicals) are trapped at the periphery of the substrate G. Specifically, when active species (radicals) containing highly reactive F, Cl, and O exist, they react with hydrogen gas at the periphery of the substrate G and do not contribute to etching such as HF, HCl, and H ₂ O And is exhausted from the chamber 2. [0051] Therefore, the amount of active species (radicals) is reduced at the periphery of the substrate G where the etching rate is increased, so that the etching rate is lowered and the etching rate in the surface of the substrate G is made uniform.

As described above, when active species (radicals) containing F, Cl, and O having high reactivity are used, these active species (radicals) can be trapped by supplying hydrogen gas as a trap gas to the peripheral portion of the substrate G (Hydrogen source), such as hydrogen radical, can function as a trap gas. Further, a trap gas other than hydrogen may be used as long as it reacts with an active species (radical) to generate a component that does not contribute to etching.

As the flow rate of the trap gas is larger, the effect of trapping the active species (radical) increases. Therefore, the distribution of the etching rate of the substrate G can be controlled by suppressing the flow rate of the trap gas. In this case, it is preferable that the flow rate of the trap gas is such that the atomic mass of the trap gas becomes 17 to 80% with respect to the atomic mass of the active species.

As a specific example, when the amorphous silicon (a-Si) film is etched, SF ₆ gas can be suitably used as the process gas. However, when hydrogen (H ₂ ) gas is used as the trap gas, It is preferable to supply the hydrogen gas at a flow rate at which the H atomic amount is 40 to 80%. A mixed gas of SF ₆ gas and oxygen (O ₂ ) gas can be suitably used as a reactive species for etching the SiN _x film. However, when hydrogen (H ₂ ) gas is used as the trap gas, It is preferable to supply the hydrogen gas at a flow rate at which the H atomic quantity is 17.1 to 34.3% with respect to the atomic amounts of F and O, When etching the Al film, BCl ₃ and Cl ₂ can be suitably used. However, when hydrogen (H ₂ ) gas is used as a trap gas, the amount of H atoms is 40 to 80 Hydrogen gas is supplied at a flow rate of 1 to 100%.

After completion of the process, the first RF power supply 14a and the second RF power supply 14b are turned off, and the supply of electricity to the adsorption electrode 6a is stopped to release the electrostatic adsorption. A lift pin (not shown) Lifts up the substrate G by opening the gate valve 32, and takes out the processed substrate G from the loading / unloading port 31.

In this embodiment, trap gas for trapping active species (radicals) is supplied to the peripheral portion of the substrate G to reduce the amount of active species (radicals) in the peripheral portion of the substrate G, The plasma etching with high uniformity in the surface can be performed by reducing the rate. As described above, since the etching rate of the peripheral portion of the substrate G can be reduced without using the rectification wall or the sacrificial material, it is necessary to optimize the rectification wall in accordance with the type of the film to be etched and the etching condition (recipe) A problem that it is troublesome and costly due to a periodic exchange of the sacrificial material and a case where a plurality of etching layers are successively treated as a problem in both of them is affected by other etching target films It is possible to solve the problem of giving up.

The supply form of the hydrogen gas which is the trap gas is not limited to the form of Fig. 1 as long as it can be supplied to the peripheral portion of the substrate G. For example, as shown in Fig. 4, the trap gas discharge nozzles 16 may be provided on the side surface of the shield ring 7, and the trap gas discharge nozzles 16 may be provided in the shower head 20, hydrogen gas may be supplied to the peripheral portion of the substrate G from above the substrate G.

≪ Second Embodiment >

Next, a second embodiment of the present invention will be described.

6 is a cross-sectional view showing a plasma etching apparatus as a plasma processing apparatus according to a second embodiment of the present invention.

As shown in FIG. 6, this plasma etching apparatus 1 'is configured as an inductively coupled plasma etching apparatus. In Fig. 6, the same reference numerals are given to the common portions in Fig. 1 and the description thereof is simplified.

The chamber 2 'of the plasma etching apparatus 1' has a ceiling wall 52 made of a dielectric material such as ceramics or quartz such as Al ₂ O ₃ and the like at a lower portion of the ceiling wall 52 , And a cross-shaped shower housing 51 for supplying a process gas is fitted in the chamber 2.

The shower housing 51 is made of a conductive material such as anodized aluminum. A gas flow path 53 extending horizontally is formed in the shower housing 51 and a plurality of gas discharge holes 54 extending downward communicate with the gas flow path 53. On the other hand, a gas inlet 24 is provided at the center of the upper surface of the top wall 52. A gas inlet 25 is connected to the gas inlet 24 like the apparatus shown in Fig. 1, A processing gas supply source 28 is connected to the supply pipe 25.

A radio frequency antenna 55 is provided along the top surface of the top wall 52. A feed line 56 is connected to the high frequency antenna 55. A matching device 57 and a plasma generation And a first high-frequency power source 58 for the source (source) are connected. Frequency electric power of, for example, 13.56 MHz is supplied from the first high-frequency power source 58 to the high-frequency antenna 55, an induction electric field is formed in the chamber 2 ', and the induction electric field causes the shower housing 51 ) Is converted into a plasma.

On the other hand, a feeder line 12 is connected to the substrate 5 of the substrate mount 4 and only the matching device 13b and the second high frequency power source 14b for applying bias are connected to this feeder line 12 .

In the plasma etching apparatus 1 'as described above, the substrate G is mounted on the substrate mounting table 4 in the same manner as in the first embodiment, and the processing gas supply pipe 25 and the shower housing 51 to the chamber 2 ', and at the same time, the pressure in the chamber 2' is adjusted to a predetermined degree of vacuum by the pressure regulating valve. Then, high-frequency power is applied from the first high-frequency power supply 58 to the high-frequency antenna 55, thereby forming an induced electric field in the chamber 2 'through the top wall 52 made of a dielectric. With the induction field formed in this manner, the processing gas is converted into plasma in the chamber 2 ', and a high-density inductively coupled plasma is generated, and plasma etching processing is performed on the substrate G. At this time, high frequency electric power for bias is applied from the second high frequency power source 14b to the substrate table 4 (base material 5) through the matching unit 13b, ions in the plasma are effectively attracted to the substrate G, A DC voltage is applied to the attracting electrode 6a from the DC power supply 15 so that the substrate G is attracted and fixed to the mounting surface of the substrate mount 4 (the insulating member 6) by the Coulomb force through the plasma .

Even in the case of etching by such an inductively coupled plasma, there are many unreacted process gases at the periphery of the substrate G, so that if the film to be etched has high chemical reactivity, The rate is increased.

Therefore, as in the first embodiment, hydrogen gas is supplied to the peripheral portion of the substrate G as a trap gas for trapping active species (radicals) in the plasma. As a result, active species (radicals) are trapped at the periphery of the substrate G. Therefore, the amount of active species (radicals) is reduced at the periphery of the substrate G where the etching rate is increased, so that the etching rate is lowered and the etching rate in the surface of the substrate G is made uniform.

<Experimental Example>

Next, an experimental example will be described.

(Experimental Example 1)

Here, as shown in Fig. 7, in a capacitively coupled plasma etching apparatus for etching a substrate of 550 x 650 mm, hydrogen gas is discharged in a range of 500 mm to a portion corresponding to the short side shield ring of the substrate mounting table And the following etching process of the film was performed with a predetermined process gas while supplying hydrogen gas at a predetermined flow rate from a plurality of gas discharge openings formed in the gas discharge nozzle. The distribution of the etching rate across the center of the substrate from the edge where hydrogen gas was supplied to the substrate at this time was measured.

ㆍ a-Si film etching

Etching was performed on the a-Si film susceptible to the influence of the F radical under the following base conditions while changing the hydrogen gas (H ₂ gas) flow rate to 0, 25, and 50 sccm.

Base condition

Pressure: 60 mTorr

Source power: 3000W

Bias power: 300W

Process gas and flow rate:

SF ₆ 100 sccm

Ar 200 sccm

The distribution of the etching rate at the time of etching such an a-Si film is shown in Fig.

As shown in this figure, when etching was performed by a conventional method not supplying H ₂ gas, the etching rate at the peripheral portion of the substrate was extremely high, and the uniformity (variability) of the etching rate was 17.9%. On the other hand, by supplying the H ₂ gas to the peripheral portion of the substrate, it is possible to control only the etching rate of the peripheral portion of the substrate without substantially affecting the etching rate to the central portion, and as the flow rate of the H ₂ gas increases, Is lowered. When the H ₂ gas flow rate is 25 sccm, the uniformity (the variability) of the etching rate becomes as small as 5.8%. When the flow rate of the H ₂ gas is 50 sccm, the etching rate at the peripheral portion of the substrate is further lowered, and the uniformity (variability) becomes as large as 17.2%. It is possible to make the etching rate lower than the etching rate at the central portion of the substrate, and it can be seen that the etching distribution can be controlled by the H ₂ flow rate.

ㆍ SiN _x film etching

The SiN _x film susceptible to the influence of the F radical and the O radical was etched by changing the hydrogen gas (H ₂ gas) flow rate to 0, 25, and 50 sccm under the following base conditions.

Base condition

Pressure: 60 mTorr

Source power: 3000W

Bias power: 300W

Process gas and flow rate:

SF ₆ 200 sccm

O ₂ 100 sccm

The distribution of the etching rate when the SiN _x film is etched is shown in Fig.

As shown in this figure, when etching was performed by a conventional method not supplying H ₂ gas, the etching rate at the peripheral portion of the substrate was extremely high, and the uniformity (variability) of the etching rate was 15.8%. On the other hand, by supplying the H ₂ gas to the peripheral portion of the substrate, it is possible to control only the etching rate of the peripheral portion of the substrate without substantially affecting the etching rate to the central portion, and as the flow rate of the H ₂ gas increases, Is lowered. When the H ₂ gas flow rate is 50 sccm, the uniformity (the variability) of the etching rate is as small as 5.3%. Even when the flow rate of the H ₂ gas is 25 sccm, the effect is large, and the uniformity (fluctuation) is 6.4%.

ㆍ Al film etching

The Al film which is susceptible to the influence of Cl radicals was etched by changing the hydrogen gas (H ₂ gas) flow rate to 0, 50, and 100 sccm under the following base conditions.

Base condition

Pressure: 20 mTorr

Source power: 1500W

Bias power: 50W

Process gas and flow rate:

BCl ₃ 200 sccm

Cl ₂ 300 sccm

The distribution of the etching rate when the Al film is etched is shown in Fig.

As shown in this figure, when etching was performed by a conventional method not supplying H ₂ gas, the etching rate at the peripheral portion of the substrate was extremely high, and the uniformity (variability) of the etching rate was 34.0%. On the other hand, it can be seen that the etching rate of the peripheral portion of the substrate can be controlled by supplying the H ₂ gas to the peripheral portion of the substrate, and the etching rate of the peripheral portion of the substrate is lowered as the flow rate of the H ₂ gas is increased. It can be seen that the uniformity (the variability) of the etching rate is greatly improved to 19.5% when the H ₂ gas flow rate is 100 sccm. Even when the flow rate of the H ₂ gas is 50 sccm, the uniformity (the fluctuation) is 28.8%, which is an improvement effect. Although it is often the case that the Al film which is susceptible to the influence of loading often uses the rectifying wall, it has been confirmed that uniformity is improved even if the rectifying wall is not provided by supplying the H ₂ gas as the trap gas to the peripheral portion of the substrate.

(Verification of supply amount of trap gas)

Next, the results of verifying the appropriate range of the supply amount of the trap gas to the process gas flow rate will be described from the above results.

The results, but by providing a gas discharging nozzle for discharging the trapped gas, H ₂ gas to one side of the substrate, supplying a trapped gas, H ₂ gas from there identify the effect of the trapped gas on the etching rate, in practice, supply The processed process gas is discharged from the center of the substrate through four sides (total circumference of 2400 mm). For this reason, in the following verification, a method of calculating the trap gas flow rate, which is required relative to the process gas, by converting the amount of the process gas into each side supplied with the trap gas, was taken.

Further, the result is a highly reactive reaction of the process gas species (active species) F, Cl, O a, by reacting with the trapped gas, H ₂ gas supplied to the substrate perimeter, HF, HCl, H ₂ O It is considered that the compound is discharged from the chamber as a compound which does not contribute to etching, and the reactive species on the periphery of the substrate is reduced. Indeed, 11 the a-Si As shown in the plasma emission spectra of the peripheral portion of the substrate when the film is etched, the more the flow rate of H ₂ gas is increased, increasing the light emission of a wavelength of 656.5㎚ H, and a wavelength of 704 Luminescence of F, which is nm is decreased. Therefore, the following verification results are premised on that point.

ㆍ Etching of a-Si film

In the above experimental example, since the SF ₆ gas is used at 100 sccm as the process gas, if the plasma is completely dissociated by the plasma, the volume becomes 7 times, and the volume flow rate becomes S of 100 sccm and F of 600 sccm. Further, as described above, since the process gas supplied to the substrate is exhausted through four sides, if the total substrate circumference is 2400 mm, the converted amount of F per 500 mm of the substrate becomes 125 sccm. On the other hand, since the H ₂ gas as the trap gas is 25 to 50 sccm, when they all dissociate, the volume becomes doubled, and H becomes 50 to 100 sccm. Converting into a ratio of atomic mass, the atomic ratio of H to the atomic mass F is in the range of 40 to 80%.

ㆍ Etching of SiN _x film

In the above experimental example, since SF ₂ gas is used as the process gas at 200 sccm and O ₂ gas is used at 100 sccm, it is assumed that S 2 is 200 sccm, F 2 is 1200 sccm, and O 2 is 200 sccm , And the volume flow rate of F and O is 1400 sccm. Therefore, the converted amount of the active species (radical) per 500 mm of the substrate is 291.7 sccm. On the other hand, since the H ₂ gas as the trap gas is 25 to 50 sccm, when they are all dissociated, H becomes 50 to 100 sccm. When converted to the atomic weight ratio, the H atomic amount relative to the active species (radical) atomic weight is in the range of 17.1 to 34.3%.

ㆍ Etching of Al film

In the above experimental example, since BCl ₃ gas is used as the process gas at 200 sccm and Cl ₂ gas is used at 300 sccm, if it is assumed that all of them are dissociated by the plasma, the volume flow rate of Cl becomes 1200 sccm. Therefore, the converted amount of Cl per 500 mm of the substrate is 250 sccm. On the other hand, the H ₂ gas which is a trap gas is 50 to 100 sccm, and when these are all dissociated, H becomes 100 to 200 sccm. In terms of the atomic weight ratio, the H atomic amount relative to the Cl atomic weight is in the range of 40 to 80%.

In the above experimental example, the flow rate of the trap gas, which is relatively required, was calculated by converting the amount of the processing gas into the atomic flow rate supplied per substrate. In practice, since the trap gas supply region is provided around the substrate, the required trap gas flow rate can be defined relative to the amount of the process gas introduced.

From the above, by supplying H ₂ gas as the trap gas so that the ratio of the H atomic amount to the atomic amount of F, Cl, and O in the process gas supplied in a unit time is in the range of 17 to 80% It is confirmed that the etching rate is effectively controlled.

(Experimental Example 2)

Next, a description will be given of the results of an experiment in which an actual process is assumed by a capacitively coupled plasma etching apparatus having the structure shown in Fig. The substrate size is 730 x 920 mm, and the trap gas is supplied around the substrate.

Here, an experiment was conducted assuming LTPS (low-temperature polysilicon) contact etching. The low-temperature polysilicon contact etching is performed by depositing a SiO ₂ film 102, an SiN _x film 103, and an SiO ₂ film 104 on a polysilicon (p-Si) film 101 as shown in FIG. 12 Structure. In the conventional etching, the etching rate of the peripheral portion of the polysilicon layer is high and the etch-off of the polysilicon film at the peripheral portion of the substrate tends to occur. Thus, the present experiment example, SiO ₂ film, in the case where with respect to the a-Si film showing the same etching properties and SiN _x film and the polysilicon film, supplying the H ₂ gas from the shower head with the other gases and, H ₂ gas Was supplied as a trap gas to the peripheral portion of the substrate, etching was performed under the following conditions.

Etching condition

Pressure: 10 mTorr

Source power: 5000W

Bias power: 5000W

Process gas and flow rate (showerhead):

C ₄ F ₈ 60 sccm

Ar 100 sccm

H ₂ 100 sccm, 0 sccm

Trap gas (H ₂ gas) flow rate (peripheral portion of substrate): 0 sccm, 100 sccm

In this case, the ratio of the atomic mass of H as the trap gas to the atomic mass of F, which is the active species, is 41.7%.

The distribution of the etching rate (etching amount) when these films are etched is shown in Figs. 13 and 14 are the results of the SiO ₂ film and the SiN _x film, respectively, but the uniformity of the etching rate in the plane is good regardless of the presence or absence of the H ₂ gas supply to the peripheral portion of the substrate. On the other hand, Figure 15 is a-Si, but the membrane results, it was the case that does not supply the H ₂ gas to the substrate perimeter, a plane of the substrate peripheral portion etching rate rises and the etching rate of the uniformity was 44%, H ₂ to a substrate peripheral portion By supplying the gas, the uniformity was drastically improved up to 10%.

Thus, by feeding H ₂ gas to the periphery of the substrate as the trap gas, only the a-Si film having a high chemical reactivity and a high etching rate at the peripheral portion of the substrate is etched without substantially affecting the etching of the SiO ₂ film or the SiN _x film It was confirmed that the distribution can be improved. Therefore, this method can be said to be a very effective method for etch-off of the polysilicon film which is likely to occur in the peripheral portion of the substrate in LTPS (low-temperature polysilicon) contact etching.

(Experimental Example 3)

Next, a trap gas supply nozzle for supplying H ₂ gas as a trap gas is provided on the side surface of the shield ring as shown in Fig. 4, and an inductively coupled plasma etching apparatus having the configuration shown in Fig. Will be described. The substrate size is 1850 x 1500 mm.

Also in this Experimental Example, an experiment was performed assuming LTPS (low temperature polysilicon) contact etching. Specifically, the etching distribution of the SiO ₂ film and the Si film depending on the presence or absence of H ₂ gas as the trap gas was examined using C ₂ HF ₅ gas, H ₂ gas and Ar gas as the process gas.

The results are shown in Fig. Fig. 16 shows the etching rate of the 1/4 portion of the substrate. C is the center of the substrate, LC is the center of the long side, SC is the center of the short side, and Edge is the corner of the substrate. 16 (a) shows the result of etching with the use of C ₂ HF ₅ : 300 sccm, H ₂ : 180 sccm, and Ar: 240 sccm, without using a trap gas. Figs. 16 (b) and 16 (c) show the results of removing H ₂ (180 sccm) in the process gas and flowing out from the trap gas discharge nozzles in the periphery of the substrate. The ratio of the atomic mass of H as the trap gas to the atomic mass of F, which is the active species in the cases of FIGS. 16 (b) and 16 (c), is 24% and 72%.

As shown in Fig. 16A, when the H ₂ gas which is a trap gas is not supplied to the peripheral portion of the substrate, the etching distribution of the SiO ₂ film is relatively uniform, but the etching rate of the Si peripheral portion of the substrate is increased. On the other hand, in Figs. 16 (b) and 16 (c) in which H ₂ gas contained in the process gas of Fig. 16 (a) is supplied as a trap gas to the peripheral portion of the substrate, the etching distribution of the SiO ₂ film is not disturbed, Distribution is improving. It was also confirmed that the result was (c) larger at 540 sccm than at (b) where the flow rate of H ₂ gas to the peripheral portion of the substrate was 180 sccm.

When a multilayer film or the like including a film to be etched having a high chemical property is to be etched, etching may be performed with a recipe for supplying the trap gas only to the etching step of the film which requires control of the etching rate of the outer peripheral portion of the substrate.

The present invention is not limited to the above-described embodiment, and various modifications are possible. For example, although plasma etching has been described as an example of the plasma treatment in the above embodiment, it is not limited to plasma etching, and other plasma treatment such as plasma CVD may be used.

Although the plasma processing apparatus of the capacitively coupled type and the inductively coupled plasma type is exemplified in the above embodiment, the plasma processing apparatus may be a device that generates plasma by another method such as microwave plasma as long as the plasma can be generated in the chamber .

The trap gas is not limited to H ₂ gas but may be any trap gas which can react with an active species such as a radical and trap it. The film to be etched is not limited to that of the above embodiment.

In the above embodiment, the present invention is applied to a glass substrate for an FPD. However, the present invention is not limited to this example. Needless to say, the present invention can be applied to other substrates such as a semiconductor substrate.

1, 1 ': Plasma etching apparatus (plasma processing apparatus)
2, 2 ': chamber (processing vessel)
4: substrate mounting table 5: substrate
6: Insulating member 7: Shield ring
14a, 58: first high frequency power source 14b: second high frequency power source
16: trap gas discharge nozzle 17: gas discharge port
18: Gas flow path 19: Trap gas supply source
20: Showerhead 25: Process gas supply pipe
28: process gas supply source 29: exhaust pipe
30: Exhaust device 31:
40: control unit 55: high frequency antenna
G: substrate

Claims (19)

1. A plasma processing apparatus for performing plasma processing on a substrate,
A plasma processing apparatus comprising: a processing container for accommodating a substrate and performing plasma processing;
A substrate mounting table for mounting the substrate in the processing container,
A processing gas supply mechanism for supplying a processing gas into the processing vessel,
An exhaust mechanism for exhausting the interior of the processing vessel,
A plasma generating means for generating a plasma of the processing gas in the processing vessel,
A trap gas supply mechanism for supplying a trap gas for trapping active species in the plasma to a peripheral portion of the substrate on the substrate mounting table;
Wherein the plasma processing apparatus further comprises:
The method according to claim 1,
Wherein the plasma treatment is a plasma etching treatment.
3. The method of claim 2,
The process gas is a gas containing at least one of F, Cl, and O,
The trap gas is a hydrogen gas
And the plasma processing apparatus.
The method according to claim 2 or 3,
Wherein the ratio of the number of atoms of the trap gas to the number of atoms of the active species in the process gas is 17 to 80%.
The method according to claim 3 or 4,
Wherein the object to be etched in the plasma etching treatment is one of an Si film, an SiN _x film, and an Al film formed on the substrate.
6. The method of claim 5,
Wherein F is used as an active species when the object to be etched is a Si film and the ratio of the number of atoms of the trapping gas to the number of atoms of the active species in the processing gas is 40 to 80%. 6. The method of claim 5,
Characterized in that F and O are used as the active species when the object to be etched is the SiN _x film and the ratio of the number of atoms of the trap gas to the number of atoms of the active species in the process gas is 17.1 to 34.3% Device.
6. The method of claim 5,
Wherein Cl is used as the active species when the object to be etched is an Al film and the ratio of the number of atoms of the trapping gas to the number of atoms of the active species in the processing gas is 40 to 80%.
9. The method according to any one of claims 1 to 8,
Wherein the trap gas supply mechanism is provided around the substrate of the substrate mounting table.
9. The method according to any one of claims 1 to 8,
The processing gas supply mechanism has a shower head for supplying a process gas into the processing container in a shower shape toward the substrate on the substrate mounting table,
Wherein the trap gas supply mechanism comprises:
And the plasma processing apparatus.
1. A plasma processing method for performing plasma processing on a substrate,
A process gas is supplied into the process container in a state where the substrate is mounted on the substrate table in the process container, a plasma of the process gas is generated in the process container, and a plasma process is performed on the substrate, Wherein a trap gas is trapped to trap active species in the plasma.
12. The method of claim 11,
Wherein the plasma treatment is a plasma etching treatment.
13. The method of claim 12,
The process gas is a gas containing at least one of F, Cl, and O,
The trap gas is a hydrogen gas
And a plasma processing method.
The method according to claim 12 or 13,
Wherein the ratio of the number of atoms of the trapping gas to the number of atoms of the active species in the processing gas is 17 to 80%.
The method according to claim 13 or 14,
Wherein the etching target of the plasma etching treatment is one of an Si film, an SiN _x film, and an Al film formed on the substrate.
16. The method of claim 15,
Wherein F is used as an active species when the object to be etched is a Si film and the ratio of the number of atoms of the trap gas to the number of atoms of the active species in the processing gas is 40 to 80%.
16. The method of claim 15,
Characterized in that F and O are used as the active species when the object to be etched is the SiN _x film and the ratio of the number of atoms of the trap gas to the number of atoms of the active species in the process gas is 17.1 to 34.3% Way.
16. The method of claim 15,
Wherein Cl is used as the active species when the object to be etched is an Al film and the ratio of the number of atoms of the trapping gas to the number of atoms of the active species in the processing gas is 40 to 80%.
A computer-readable storage medium storing a program for controlling a plasma processing apparatus,
Wherein the program causes the computer to control the plasma processing apparatus so that the plasma processing method according to any one of claims 11 to 18 is executed at the time of execution.

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