CN107808824A - plasma etching method - Google Patents

Abstract

The invention provides a plasma etching method, which can inhibit the consumption of aluminum-containing substances when a Ti/Al/Ti laminated film is subjected to plasma etching by using chlorine-containing gas in a processing container with the inner surface provided with the aluminum-containing substances. The plasma etching method of the present invention includes: a step of loading a substrate having a lower Ti film, a Ti/Al/Ti laminated film in which an Al film and an upper Ti film are laminated, and a patterned resist layer formed thereon, into a processing container having an aluminum-containing material on at least a part of an inner surface thereof; and an etching step of generating plasma containing an etching gas containing a chlorine-containing gas and a nitrogen gas, and plasma-etching the Ti/Al/Ti laminated film by the generated plasma using the resist layer as a mask.

Description

plasma etching method

technical field

The present invention relates to plasma etching method

Background technique

Thin Film Transistor (TFT: Thin Film Transistor) used in FPD (Flat Panel Display) is formed by sequentially laminating a gate electrode, a gate insulating film, a semiconductor layer, etc. while patterning on a substrate such as a glass substrate.

For example, when manufacturing a channel-etched TFT with a bottom-gate structure, a gate electrode, a gate insulating film, and an oxide semiconductor film are sequentially formed on a glass substrate, and then a metal film is formed on the oxide semiconductor film. The metal film is subjected to plasma etching, thereby forming a source electrode and a drain electrode. Ti/Al/Ti laminated films are often used as metal films for source electrodes and drain electrodes, and Patent Document 1 describes the use of Cl ₂ gas and BCl ₃ gas as the etching method for forming Ti/Al/Ti laminated films. gas.

prior art literature

Patent Document 1: Japanese Patent Laid-Open No. 2000-235968

However, in a plasma etching apparatus that performs plasma etching, aluminum whose inner surface is anodized is used as a processing container (chamber) for processing, and corrosion resistance is imparted by an anodized film. However, in Patent Document 1 When a chlorine-containing gas such as Cl ₂ gas and BCl ₃ gas is used as the etching gas, the anodic oxide film on the inner wall of the chamber is etched and consumed, and it can be judged that the anodic oxide film disappears when the treatment is repeated.

Contents of the invention

Therefore, the technical problem to be solved by the present invention is to provide a plasma etching method, in which a chlorine-containing gas is used to perform plasma etching on a Ti/Al/Ti laminated film in a processing container having an aluminum-containing substance such as an anodized film on the inner surface. During bulk etching, the consumption of aluminum-containing materials can be suppressed.

In order to solve the above-mentioned technical problems, the present invention provides a plasma etching method, which includes: a process of carrying a substrate into a processing container in which at least a part of the inner surface is formed of an aluminum-containing substance, and the above-mentioned substrate has a lower Ti film, an Al film and an upper layer. a Ti/Al/Ti laminated film in which a Ti film is laminated, and a patterned resist layer is formed thereon; and an etching process of generating plasma containing an etching gas containing chlorine gas and nitrogen gas to The above-mentioned resist layer is used as a mask, and the above-mentioned Ti/Al/Ti laminated film is plasma-etched using the above-mentioned plasma.

In the present invention, the above-mentioned etching gas and the above-mentioned nitrogen gas may be supplied into the above-mentioned processing container, and plasma formation may be performed in the above-mentioned processing container.

In the above-mentioned etching step, the above-mentioned aluminum-containing substance on the inner surface of the above-mentioned processing container can be nitrided by using the above-mentioned nitrogen gas transformed into plasma. In addition, in the etching step, components of the resist layer ashed by the nitrogen plasma can be deposited on the inner surface of the processing container.

As the above-mentioned etching gas, chlorine-containing gas and inert gas can be used. In addition, the above-mentioned chlorine-containing gas may include chlorine gas and boron trichloride gas.

The ratio of the flow rate of the chlorine-containing gas to the flow rate of the nitrogen gas is preferably in the range of 6:1 to 10:1.

The aluminum-containing substance on the inner surface of the processing container may be an anodized film formed by anodizing aluminum.

The effect of the invention

According to the present invention, the plasma of etching gas containing chlorine gas and nitrogen gas is generated, and the Ti/Al/Ti laminated film is plasma etched using the generated plasma using the resist layer as a mask. Therefore, it is possible to utilize The action of nitrogen plasma suppresses the consumption of aluminum-containing substances.

Description of drawings

FIG. 1 is a cross-sectional view showing a plasma etching apparatus for carrying out a plasma etching method according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a plasma etching method according to an embodiment of the present invention performed by the plasma etching apparatus of FIG. 1 .

3 is a cross-sectional view showing the structure of a substrate used in the plasma etching method according to the embodiment of the present invention.

4 is a cross-sectional view showing a state after etching a Ti/Al/Ti multilayer film on the substrate having the structure shown in FIG. 3 .

FIG. 5 is a diagram for explaining a mechanism of suppressing consumption of an anodized film by plasma of N ₂ gas.

FIG. 6 is a diagram showing the bonding positions of Si chips on the chamber wall in Experimental Example 1. FIG.

7 is a graph showing the removal amount of the Si chip at each position in FIG. 6 when plasma etching was performed in Experimental Example 1 without adding N ₂ gas and in the case of adding N ₂ gas.

FIG. 8 is a view showing positions where the film thickness of the anodized film on the chamber wall portion was measured in Experimental Example 2. FIG.

FIG. 9 is a graph showing the amount of change in film thickness at each position in FIG. 8 when plasma etching was performed without adding N ₂ gas and with adding N ₂ gas in Experimental Example 2. FIG.

Explanation of reference signs

1: main container; 1a: anodized film; 2: dielectric body wall; 4: chamber (processing container); 11: spray frame; 13: high-frequency antenna; 15: high-frequency power supply; 20: processing Gas supply mechanism; 30: substrate mounting table; 32: electrostatic chuck; 33: shielding ring; 60: exhaust mechanism; 100: plasma etching device; 101: glass substrate; 102: grid electrode; 103: grid insulating film 104: semiconductor film; 105: Ti/Al/Ti stacked film; 105a: upper Ti film; 105b: Al film; 105c: lower Ti film; 106: photoresist layer; S: substrate.

Detailed ways

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

<Plasma etching device>

FIG. 1 is a cross-sectional view showing a plasma etching apparatus for carrying out a plasma etching method according to an embodiment of the present invention.

The plasma etching apparatus 100 is used to etch the Ti/Al/Ti laminated film of the substrate S, and has, for example, an airtight main body container 1 in the shape of a square tube made of aluminum whose inner wall surface is anodized. An anodized film 1 a having a thickness of about 30 to 70 μm is formed on the inner surface of the main body container 1 . The portion where the anodized film 1a is formed is not limited to the entire inner surface of the main body container 1, but may be only a part thereof, for example, only the side surface. The main body container 1 is grounded. The main body container 1 is divided up and down by a dielectric body wall 2, and the upper side is an antenna container 3 defined as an antenna chamber, and the lower side is a chamber (processing container) 4 defined as a processing chamber. The dielectric wall 2 constitutes the ceiling wall of the chamber 4 and is made of ceramics such as Al ₂ O ₃ , quartz, or the like. The horizontal section of the chamber 4 is rectangular with long and short sides.

A support frame 5 protruding inward is provided between the side wall 3 a of the antenna container 3 and the side wall 4 a of the chamber 4 in the main body container 1 , and the dielectric body wall 2 is placed on the support frame 5 .

A shower frame 11 for supplying process gas is fitted in the lower portion of the dielectric wall 2 . The shower frame 11 is suspended from the ceiling of the main body container 1 by a plurality of suspension rods (not shown).

The shower frame 11 is made of a conductive material, for example, aluminum whose inner surface or outer surface is anodized. The shower frame 11 is formed with a gas flow path 12 extending horizontally, and the gas flow path 12 communicates with a plurality of gas discharge holes 12a extending downward.

On the other hand, a gas supply pipe 21 is provided at the center of the upper surface of the dielectric body wall 2 so as to communicate with the gas flow path 12 . The gas supply pipe 21 penetrates from the top of the main body container 1 to the outside thereof, and branches into branch pipes 21a and 21b. A chlorine-containing gas supply source 22 for supplying chlorine-containing gas such as chlorine gas (Cl ₂ gas) and boron trichloride gas (BCl ₃ gas) is connected to the branch pipe 21 a. In addition, a N ₂ gas supply source 23 for supplying nitrogen gas (N ₂ gas) is connected to the branch pipe 21b. The branch pipes 21a and 21b are provided with a flow controller such as a mass flow controller or a valve system.

The gas supply pipe 21 , the branch pipes 21 a, 21 b, the chlorine-containing gas supply source 22 , the N ₂ gas supply source 23 , and the flow controller and valve system constitute the processing gas supply mechanism 20 .

Here, as the chlorine-containing gas, Cl ₂ gas or BCl ₃ gas may be used alone, or other gases such as carbon tetrachloride (CCl ₄ ) gas may be used as part or all of the chlorine-containing gas.

A radio frequency (RF) antenna 13 is arranged inside the antenna case 3 . The high-frequency antenna 13 has a structure in which an antenna line 13a made of a highly conductive metal such as copper or aluminum is arranged in a conventionally used arbitrary shape such as a loop or a spiral. The high-frequency antenna 13 may be a multiple antenna having a plurality of antenna parts. The radio-frequency antenna 13 is separated from the dielectric body wall 2 by a spacer 17 formed of an insulating member.

The feed member 16 extending upward from the antenna case 3 is connected to the terminal 18 of the antenna wire 13a. The power supply line 19 is connected to the upper end of the power supply unit 16 , and the matching unit 14 and the high-frequency power supply 15 are connected to the power supply line 19 . Then, by supplying high-frequency power with a frequency of, for example, 13.56 MHz from the high-frequency power supply 15 to the high-frequency antenna 13, an induced electric field is formed in the chamber 4, and the process gas supplied from the shower frame 11 is converted into plasma by the induced electric field. , generating an inductively coupled plasma.

A substrate mounting table 30 on which a substrate S is mounted is provided via a frame-shaped spacer 26 made of an insulator on the bottom wall of the chamber 4 . The substrate mounting table 30 includes: a substrate 31 disposed on the spacer 26, an electrostatic chuck 32 disposed on the substrate 31, and a shield ring formed of an insulator covering the side walls of the substrate 31 and the electrostatic chuck 32. 33. The substrate 31 and the electrostatic chuck 32 have a rectangular shape corresponding to the shape of the substrate S, and the substrate mounting table 30 is formed in a square plate shape or a column shape as a whole. The spacer 26 and the shield ring 33 are made of insulating ceramics such as alumina.

The electrostatic chuck 32 includes a dielectric layer 45 formed of a ceramic sprayed film formed on the surface of the base material 31 , and an adsorption electrode 46 provided inside the dielectric layer 45 . The adsorption electrode 46 can take various forms such as a plate shape, a film shape, a lattice shape, and a mesh shape. The adsorption electrode 46 is connected to a DC power supply 48 via a power supply line 47 , and a DC voltage is applied to the adsorption electrode 46 . The power supply to the adsorption electrode 46 is turned on and off by a switch (not shown). By applying a DC voltage to the adsorption electrode 46 , an electrostatic adsorption force such as Coulomb force or Johnson-Rabeck force is generated, and the substrate S is adsorbed. Ceramics such as alumina (Al ₂ O ₃ ) or yttrium oxide (Y ₂ O ₃ ) can be used as the dielectric layer 45 of the electrostatic chuck 32 .

A high-frequency power source 53 for applying a bias voltage is connected to the base material 31 through a power supply line 51 . In addition, a matching unit 52 is provided between the base material 31 of the power supply line 51 and the high-frequency power source 53 . The high-frequency power supply 53 is used to introduce ions into the substrate S on the base material 31 , and can use a frequency in the range of 50 kHz to 10 MHz, for example, 3.2 MHz.

In addition, a temperature adjustment mechanism and a temperature sensor (both not shown) for controlling the temperature of the substrate S are provided in the base material 31 of the substrate mounting table 30 . In addition, in the state where the substrate S is placed on the substrate mounting table 30, a heat transfer gas supply mechanism (not shown) for supplying a heat transfer gas for heat transfer, such as He gas, is provided between the substrate S and the substrate mounting table 30. Show). In addition, on the substrate mounting table 30, a plurality of lift pins (not shown) for transferring the substrate S are provided so as to protrude and sink relative to the upper surface of the electrostatic chuck 32. 32 is carried out by the lift pin in the state where the upper surface protrudes upward.

A loading and unloading port 55 for loading and unloading the substrate S into and out of the chamber 4 is provided on the side wall 4 a of the chamber, and the loading and unloading port 55 can be opened and closed by a gate valve 56 . By opening the gate valve 56 , the substrate S can be loaded and unloaded from a transfer device (not shown) in an adjacent vacuum transfer chamber (not shown) through the loading and unloading port 55 .

A plurality of exhaust ports 59 (only two are shown) are formed at the edge or corner of the bottom wall of the chamber 4 , and each exhaust port 59 is provided with an exhaust mechanism 60 . The exhaust mechanism 60 has: an exhaust pipe 61 connected to the exhaust port 59, an automatic pressure control valve (APC) 62 for controlling the pressure in the chamber 4 by adjusting the opening of the exhaust pipe 61, and a The gas piping 61 is a vacuum pump 63 for exhausting the inside of the chamber 4 . Then, the inside of the chamber 4 is evacuated by the vacuum pump 63, and the opening degree of the automatic pressure control valve (APC) 62 is adjusted during the plasma etching process to set and maintain a predetermined vacuum atmosphere in the chamber 4 .

The plasma etching apparatus 100 further includes a control unit 70 . The control unit 70 is composed of a computer including a CPU and a storage unit, and each component of the plasma etching apparatus 100 (the flow controller and valve system of the processing gas supply mechanism 20, the high-frequency power supply 15, 53, the automatic pressure control valve (APC) 62, DC power supply 48, etc.) to perform control so as to perform predetermined processing based on the processing plan (program) stored in the storage unit. The solution is stored in a storage medium such as a hard disk, an optical disk, or a semiconductor memory.

<Plasma etching method>

Next, a plasma etching method according to an embodiment of the invention implemented by the above plasma etching apparatus 100 will be described based on the flowchart of FIG. 2 .

First, the gate valve 56 is opened, and the Ti/Al/Ti stack shown in FIG. A substrate S on which a film is deposited and a patterned photoresist layer is formed thereon is placed on the substrate stage 30 (step 1). After the transfer mechanism is withdrawn from the chamber 4, the gate valve 56 is closed.

The substrate S is used to form a channel-etched bottom-gate TFT. In more detail, as shown in FIG. There is a semiconductor film 104 formed of an oxide semiconductor such as IGZO, and a Ti/Al/Ti laminated film 105 serving as a source electrode and a drain electrode is formed thereon. The Ti/Al/Ti laminated film 105 has an upper Ti film 105a, a lower Ti film 105c, and an Al film 105b disposed therebetween. The Al film 105b may be Al alone or an Al alloy such as Al—Si. The film thickness of the upper layer Ti film 105a and the lower layer Ti film 105c is about 30 to 100 nm, and the film thickness of the Al film 105b is about 300 to 1000 nm. A patterned photoresist layer 106 as an etching mask is formed over the Ti/Al/Ti laminated film 105 .

In this state, the pressure in the chamber 4 is adjusted to a predetermined degree of vacuum by the automatic pressure control valve (APC) 62, and the processing gas is supplied from the processing gas supply mechanism 20 through the shower frame 11 into the chamber. , an etching gas (such as Cl ₂ gas+BCl ₃ gas) and N ₂ gas containing chlorine gas, the above-mentioned gas is plasmaized, and the Ti/Al/Ti laminated film 105 is plasma etched as shown in FIG. 4 ( Step 2).

At this time, the substrate S is attracted by the electrostatic chuck 32, and the temperature is adjusted by a temperature adjustment mechanism (not shown).

In Step 2, first, an etching gas containing chlorine gas and N ₂ gas are supplied as process gases into the chamber. At this time, as the chlorine-containing gas constituting the etching gas, for example, Cl ₂ gas and BCl ₃ gas can be used. In addition, as the etching gas, inert gas such as Ar gas may be supplied in addition to chlorine-containing gas.

Next, when the processing gas is converted into plasma, a high frequency of, for example, 13.56 MHz is supplied from the high frequency power supply 15 to the high frequency antenna 13 , thereby forming a uniform induced electric field in the chamber 4 via the dielectric wall 2 . At this time, a high-frequency bias voltage of, for example, 3.2 MHz is supplied to the base material 31 from the high-frequency power supply 53 , and it functions to introduce appropriate ions into the substrate S.

By the induced electric field formed as described above, high-density inductively coupled plasma is generated, and chlorine-containing gas Cl ₂ gas and BCl ₃ gas supplied as etching gas are turned into plasma. At this time, N ₂ gas is also plasmaized.

Then, the Ti/Al/Ti laminated film 105 of the substrate S is subjected to plasma etching for forming the source electrode and the drain electrode by the plasmaized Cl ₂ gas and BCl ₃ gas.

At this time, when the supplied processing gas is only a chlorine-containing gas as an etching gas, the Ti/Al/Ti multilayer film 105 is etched by the plasma of the chlorine-containing gas, and the Ti/Al/Ti multilayer film 105 is The anodized film 1a formed of Al ₂ O ₃ on the surface is consumed by sputtering. In particular, by using a gas containing BCl ₃ gas such as the mixed gas of Cl ₂ gas and BCl ₃ gas in this example as the chlorine-containing gas, the consumption of the anodic oxide film 1a becomes severe due to the reducing action of B. Once the anodized film 1a is consumed as described above and eventually the anodized film 1a disappears, the etching resistance of the inner surface of the chamber 4 cannot be ensured.

Therefore, in the present embodiment, N ₂ gas is supplied in addition to chlorine-containing gas as an etching gas, and N ₂ gas is also converted into plasma. Although the plasma of _N2 gas hardly participates in the etching of the Ti/Al/Ti laminated film 105, it has the effect of nitriding the Al in the anodized film 1a as shown in FIG. The improvement of plasma resistance plays a protective role; as shown in (b) of FIG. The surface of the oxide film 1a serves to protect the anodic oxide film 1a.

These two actions can suppress the consumption of the anodized film 1 a on the inner surface of the chamber 4 . Therefore, it is possible to prevent the decrease in plasma resistance caused by the disappearance of the anodized film 1a.

In this case, the chlorine-containing gas:N ₂ gas (flow ratio) is preferably in the range of 6:1 to 10:1. In addition, when Cl ₂ gas and BCl ₃ gas are used as the chlorine-containing gas, it is preferable that Cl ₂ gas:BCl ₃ gas (flow ratio) is in the range of 1.5:1 to 5:1. In addition, when an inert gas such as Ar gas is used as the etching gas, it is preferable that the chlorine-containing gas:inert gas (flow ratio) is in the range of 1.5:1 to 5:1.

As shown in this example, the preferred conditions for plasma etching using _Cl2 gas and _BCl3 gas as etching gas are:

Pressure in the chamber: 1.33～2.66Pa (0.01～0.02Torr)

Cl ₂ gas flow rate: 600～1000mL/min(sccm)

Flow rate of BCl ₃ gas: 300～500mL/min(sccm)

Flow rate of _N2 gas: 100～200mL/min(sccm)

Power of high-frequency power supply 15 for inductively coupled plasma generation: 2000-3000W

The power of the high-frequency power supply 53 for high-frequency bias voltage: 1000-2000W.

After performing the above-mentioned plasma etching process for a predetermined period of time, the process gas is stopped, the chamber 4 is evacuated by the vacuum pump 63 and purged with an appropriate purge gas, the gate valve 56 is opened, and a transfer mechanism (not shown) is used to remove the gas. The processed substrate S is unloaded through the loading/unloading port 55 (step 3).

<Experiment example>

[Experimental example 1]

In Experimental Example 1, Si chips were pasted at multiple positions shown in FIG. 6 on the long side walls and the short side walls of the rectangular chamber of the device shown in FIG. 1 , and Cl was used as the etching gas. ₂ gas and BCl ₃ gas, for the case of generating inductively coupled plasma without adding N ₂ gas and the case of adding N ₂ gas to generate inductively coupled plasma, the amount of removal of Si chips was studied.

The bonding positions of the Si chips in this experimental example are the positions of No. 1 to No. 5 on the long side walls, and the positions of No. 6 to No. 10 on the short side. In addition, the conditions are pressure: 15 mTorr (2 Pa), gas flow: Cl ₂ /BCl ₃ /N ₂ =630/315/0 or 100 sccm, RF power (source/bias): 2900/1940W.

Figure 7 shows the results. As shown in the figure, when _N2 gas is not supplied, the closer to the upper part of the wall of the chamber and the closer to the center, the stronger the sputtering force of the plasma, and the amount of Si removal is very large. However, by supplying 100 sccm In the N ₂ gas, the amount of Si removal was significantly reduced regardless of the position of the chamber wall, and it was confirmed that the effect of protecting from the sputtering of the plasma was high by including N ₂ in the plasma.

[Experimental example 2]

In Experimental Example 2, using the apparatus of FIG. ₁ , Cl2 gas and _BCl3 gas were used as etching gas, and 10000 substrates were mass-produced (plasma etched) for the case where _N2 gas was not added and the case where _N2 gas was added Then, the film thickness of the anodized film was investigated at a plurality of positions shown in FIG. 8 on the inner wall of the chamber. Among them, the flow rate of Cl ₂ gas is 400 to 1100 sccm, the flow rate of BCl ₃ gas is 200 to 600 sccm, and when N ₂ gas is added, the flow rate is 50 to 200 sccm.

The film thickness of the anodized film was determined by measuring the increase or decrease (change amount) of the overall thickness of the film adhering to the surface of the aluminum base. Fig. 9 is a graph showing the change amount (unit: μm) of the film thickness at each position in Fig. 8 when N ₂ gas is not added and when N ₂ gas is added, and the film is represented by a negative value In the case of disappearance (decrease), the case of increase is indicated by a positive numerical value. As shown in Figure 9, in the case of no addition of N ₂ , the consumption of the anodic oxide film can be seen. In the upper center of the long side wall where the consumption is most severe, the thickness of the film disappears to -39 μm; In the case of N ₂ , the consumption of the anodic oxide film is suppressed, and the upper center of the long side wall is only -3 μm. In addition, the other parts increased rather than the initial film thickness. From this, it was confirmed that the addition of N ₂ gas can protect the anodic oxide film and obtain the effect of suppressing the consumption of the anodic oxide film.

[Experimental example 3]

In Experimental Example 3, the effect of adding N ₂ gas on the etching process was confirmed.

Here, Cl gas was used as an etching gas, and the center, middle, and edge of the substrate _were obtained when plasma etching was performed for the case of not adding _N gas and the case of adding N _gas . The taper angle of the etched part of the Ti/Al/Ti stack film at (edge). The results confirm that: without adding _N2 gas, the taper angle is the center: 82.1 °, the middle: 74.4 °, the edge: reverse taper (excessive cutting of the etched part intruded into the resist layer); In the case of N ₂ gas, the cone angle is center: 84.6°, middle: 80.7°, edge: 81.8°, there is no adverse effect on the etching process, but the protective effect brought by adding N ₂ gas, the center and The shape difference of the edge is reduced.

<Other applications>

In addition, this invention is not limited to the said embodiment, Various deformation|transformation is possible within the scope of the idea of this invention. For example, in the above-mentioned embodiment, an example in which an inductively coupled plasma etching device is used as a plasma etching device is illustrated, but it is not limited to this, and other plasma etching devices such as a capacitively coupled plasma etching device or a microwave plasma etching device may be used. device.

In addition, in the above-mentioned embodiment, the case of using a chamber having an aluminum anodized coating on the inner surface was exemplified, but the present invention is applicable to a case where at least a part of the inner surface of the chamber is an aluminum-containing substance.

Claims (8)

1. A plasma etching method, characterized in that, comprising: A step of carrying a substrate having a Ti/Al/Ti laminated film in which a lower Ti film, an Al film, and an upper Ti film are laminated into a processing container in which at least a part of the inner surface is formed of an aluminum-containing substance. having a patterned resist layer formed thereon; and In the etching step, plasma of an etching gas containing chlorine gas and nitrogen gas is generated, and the Ti/Al/Ti laminated film is plasma-etched using the plasma using the resist layer as a mask. 2. The plasma etching method according to claim 1, characterized in that: The etching gas and the nitrogen gas are supplied into the processing container, and plasma is formed in the processing container. 3. The plasma etching method according to claim 1 or 2, characterized in that: In the etching step, the aluminum-containing substance on the inner surface of the processing container is nitrided by using the plasmaized nitrogen gas. 4. The plasma etching method according to any one of claims 1 to 3, characterized in that: In the etching step, components of the resist layer obtained by plasma ashing of the nitrogen gas are deposited on the inner surface of the processing container. 5. The plasma etching method according to any one of claims 1 to 4, characterized in that: A chlorine-containing gas and an inert gas are used as the etching gas. 6. The plasma etching method according to any one of claims 1 to 5, characterized in that: The chlorine-containing gas includes chlorine gas and boron trichloride gas. 7. The plasma etching method according to any one of claims 1 to 6, characterized in that: The ratio of the flow rate of the chlorine-containing gas to the flow rate of the nitrogen gas is in the range of 6:1˜10:1. 8. The plasma etching method according to any one of claims 1 to 7, characterized in that: The aluminum-containing substance on the inner surface of the processing container is an anodized film formed by anodizing aluminum.