JP2002198360A - Etching method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching method by which upper layer aluminum based films can be etched in good shape, and lower layer silicon base films can be etched with good controllability, in the etching of a laminated structure constituted of the upper layer aluminum based films an the lower layer silicon based films. SOLUTION: This etching method of the laminated structure constituted of the upper layer aluminum based films and the lower layer silicon base films comprises a first process in which the upper layer aluminum based films (46, 47, 48) are etched by plasma of a process gas which includes a chlorine containing gas and a hydrogen containing gas, a second process to confirm stoppage or considerable slowing down of the etching in the first process appropriately, and a third process in which the lower layer silicon based films (44, 45) are etched by plasma of a process gas which includes a fluorine containing gas, being switched after confirming stoppage or considerable slowing down of the etching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquid crystal display (L).
The present invention relates to an etching method for etching a laminated structure of an upper Al-based film and a lower Si-based film included in a thin film transistor (TFT) used for a CD).

[0002]

2. Description of the Related Art Active matrix L using TFT
A CD (TFT-LCD) is extremely used as a display device for a personal computer or the like instead of a CRT because it has extremely high display performance and can be made thin.

When manufacturing a TFT structure used for an LCD, a gate electrode is formed on a glass substrate, and a gate insulating film is formed thereon. Then, a semiconductor layer and a film for forming a source electrode and a drain electrode are sequentially formed thereon, and the source electrode, the drain electrode, and a channel portion are formed by etching. Specifically, amorphous Si (a-S
i) A film and n ⁺ a-Si are formed, and Ti-A
An l-Ti laminated film is formed, and this laminated film and n ⁺ a-S
Etching to the middle of the a-Si film via i
A source electrode and a drain electrode are formed on the Al-Ti laminated film, and a channel portion is formed on the a-Si film.

In this etching, conventionally, first, C
by etching the laminated film of Ti-Al-Ti as Al-based film to form a source electrode and a drain electrode by l ₂ (hereinafter, referred to as "SD etch"), after detecting the end point of this SD etching, an etching gas Switching to a fluorine (F) -based gas to switch the n ⁺ a-Si film and aS
A channel is formed by etching the i-film (hereinafter, referred to as “channel etching”). Channel etching is an important process for determining TFT characteristics.
-It is necessary to etch the etching amount of the Si film uniformly and uniformly. Also, a-S after channel etching
It is said that the thinner the i film, the better the characteristics of the TFT.

[0005]

In the above-mentioned SD etching, it is necessary to have a good shape. In order to perform a desired shape control, a high bias power is required in the etching. However, in this case, since reactive ion etching is performed, n ⁺ a-Si of Al and Ti is used.
The selectivity to is low. In addition, since the thickness of the Ti—Al—Ti laminated film is not completely uniform and the etching rate is not completely in-plane, it is necessary to perform over-etching even after the end point is detected. As a result, the underlying n ⁺ a-Si
Since the film is etched, it is difficult to control the etching distribution in the channel portion where the a-Si film needs to remain thin and uniform. On the other hand, when the SD etching is performed with a low bias power, the etching rate of the underlying n ⁺ a-Si film is reduced, and the etching of the channel portion is easily controlled, but the Al film is side-etched and the shape is deteriorated. And the deposition of the a-Si film occurs.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and in etching a laminated structure of a lower Si-based film and an upper Al-based film, the upper Al-based film is etched with good shape. It is another object of the present invention to provide an etching method capable of etching a lower Si-based film with good controllability.

[0007]

According to a first aspect of the present invention, there is provided an etching method for etching a laminated structure of an upper Al-based film and a lower Si-based film. The upper Al-based film is formed by adding Cl-containing gas and H
After the first step of etching by the plasma of the processing gas containing the containing gas, the second step of confirming the stop or remarkable deceleration of the etching of the first step, and after confirming the stop or remarkable deceleration of the etching, the F-containing gas is removed. A third step of etching the lower Si-based film by plasma of a processing gas containing the etching gas.

According to a second aspect of the present invention, a laminated film having a Si-based film formed on a substrate via a gate electrode and a gate insulating film and an Al-based film formed thereon is etched. An etching method for a thin film transistor, wherein the Al-based film is used as a source electrode and a drain electrode, and the Si-based film is used as a channel portion, wherein the Al-based film is a processing gas containing a Cl-containing gas and an H-containing gas. A first step of etching with plasma, a second step of confirming the stop or significant deceleration of the etching in the first step, and after confirming the stop or significant deceleration of the etching, the plasma of a processing gas containing an F-containing gas is used to perform the etching. S
and a third step of etching the i-type film.

According to a third aspect of the present invention, there is provided an amorphous Si film formed on a substrate via a gate electrode and a gate insulating film, and an n ⁺ type amorphous S film formed thereon.
etching a laminated film having an i-film and a three-layer structure film further formed thereon and having a barrier metal formed on both sides of an Al-containing film, and using the three-layer structure film as a source electrode and a drain electrode; An etching method for a thin film transistor, wherein the amorphous Si film is used as a channel portion, wherein at least the three-layer structure film is etched by a plasma of a processing gas containing a Cl-containing gas and an H-containing gas to form a source electrode and a drain electrode. a first step of forming a second step of confirming the etch stop or significant speed reduction of the first step, after confirming the etch stop or significant speed reduction, said by the plasma of the processing gas containing the F-containing gas n ⁺ -Type amorphous Si film and a third method of forming a channel portion by etching the amorphous Si film
And an etching method.

In the present invention, the upper Al-based film is formed of Cl
Since the etching is performed by the plasma of the processing gas containing the H-containing gas and the H-containing gas, the etching of the Al-based film can be etched with good shape by the etching action by the Cl-containing gas and the protection action by the H-containing gas. The etching can be stopped or rapidly decelerated at a desired position by the action of the gas, and after confirming this, the Si-based film can be etched with good controllability by etching with a processing gas containing an F-containing gas. .

[0011] This is because C in the photoresist is sputtered by the plasma of the H-containing gas and H on the surface to be etched.
It is considered that a film is formed due to the polymerization reaction occurring and inhibits etching. In other words, this film prevents side etching of the Al-based film and improves the shape. In addition, the deposition of this film can stop etching at an appropriate portion, thereby improving the selectivity to the underlying Si-based film. can do. From such a viewpoint, Al
When etching the system film, it is preferable that the conditions be such that a photoresist serving as an etching mask is sputtered by plasma of a processing gas containing a Cl-containing gas and an H-containing gas. In addition, when the Al-based film is etched, by controlling the amount of the H-containing gas in the processing gas, it is possible to control the position where the etching stops or a significant deceleration occurs.

[0012]

Embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 1 is a sectional view showing a plasma etching apparatus for performing an etching method according to one embodiment of the present invention. The plasma etching apparatus 1 is configured as a capacitively coupled parallel plate plasma etching apparatus.

The plasma etching apparatus 1 has, for example, a chamber 2 formed into a rectangular cylindrical shape made of aluminum whose surface is anodized (anodized). A prism-shaped susceptor support 3 made of an insulating material is provided at the bottom of the chamber 2, and an LCD, which is a substrate to be processed, is provided on the susceptor support 3.
A susceptor 5 for mounting the glass substrate G is provided. The susceptor 5 is made of alumite-treated (anodized) aluminum and functions as a lower electrode. The insulating member 4 is provided on the outer periphery and the upper surface periphery of the susceptor 5.

Above the susceptor 5, there is provided a frame-shaped clamp member 6 for mechanically clamping the periphery of the substrate G from above. The clamp member 6 is raised and lowered by a lifting mechanism 7 including a cylinder mechanism and the like.

A power supply line 12 for supplying high-frequency power is connected to the susceptor 5, and a matching unit 13 and a high-frequency power supply 14 are connected to the power supply line 12. For example, 13.56 MHz high frequency power is supplied to the susceptor 5 from the high frequency power supply 14. By supplying power from the high-frequency power supply 14, the processing gas is turned into plasma,
A bias power is supplied to the susceptor 5 serving as a lower electrode.

Above the susceptor 5, there is provided a shower head 15 which functions as an upper electrode facing the susceptor 5 in parallel. This shower head 15
Is supported at the upper part of the chamber 2, has a space 17 therein, and has a large number of discharge holes 18 for discharging a processing gas on a surface facing the susceptor 5. The shower head 15 is grounded, and forms a pair of parallel plate electrodes together with the susceptor 5.

A gas inlet 19 is provided on the upper surface of the shower head 15, and a gas supply pipe 20 is connected to the gas inlet 19, and a processing gas supply mechanism 21 is connected to the gas supply pipe 20. It is connected. The processing gas supply mechanism 21 supplies Cl ₂ gas as a Cl-containing gas.
A _second supply source 22, a _{H 2} supply source 23 for supplying _{H 2} gas as H-containing gas, a SF ₆ supply source 24 for supplying SF ₆ as F-containing gas, supplying HCl gas HCl
A supply source 25, a He supply source 26 for supplying He gas,
A BCl ₃ supply source 27 for supplying a BCl ₃ gas. These Cl ₂ supply source 22, H ₂ supply source 23, SF
₆ supply 24, HCl supply 25, He supply 26 and BCl ₃ supply 27 have gas lines 22 respectively.
a, 23a, 24a, 25a, 26a, 27a are connected. These gas lines are connected to a gas supply pipe 20, and gas from each supply source reaches the shower head 15 through each gas line and the gas supply pipe 20, and is discharged from the discharge hole 18 of the shower head. I have. Each gas line has a valve 32 and a mass flow controller 33
Are provided.

An exhaust pipe 3 is provided at the bottom of the side wall of the chamber 2.
The exhaust pipe 34 is connected to an exhaust device 35.
Is connected. The exhaust device 35 is provided with a vacuum pump such as a turbo-molecular pump.
The inside is evacuated to a predetermined reduced pressure atmosphere. Further, a substrate loading / unloading port 36 and a gate valve 37 for opening and closing the substrate loading / unloading port 36 are provided on the side wall of the chamber 2, and the substrate G is adjacent to the load lock chamber (with the gate valve 37 opened). (Not shown)
And is transported between them. On the side wall of the chamber 2 opposite to the gate valve 37 side, a window 38 for transmitting light from the plasma is formed, and the plasma light transmitted from the window 38 is separated to obtain the emission spectra of Al and Ti. A plasma light detection device 39 for detection is provided.

Next, a processing operation when the embodiment of the present invention is implemented by the plasma etching apparatus 1 will be described. First, a substrate G having a layer structure shown in FIG. 2 is prepared. In the substrate G, a gate electrode 42 is partially formed on a glass panel (substrate) 41.
2 and a gate insulating film 4 on the entire surface of the glass panel 41.
An a-Si film 44 and an n ⁺ a-Si film 45 are formed on the gate insulating film 43 as a Si-based film for forming a transistor, and a source electrode and a drain electrode are further formed thereon. The lower Ti film 46, the Al film 47, and the upper Ti film 48 as Al-based films to be formed.
Is formed. Then, a photoresist layer 49 as an etching mask is formed on the Ti film 48.
Are formed. These Ti films 46 and 48 function as barrier metals. TiN (titanium nitride) or the like may be used as the barrier metal instead of Ti (titanium).

After the gate valve 37 is opened, the substrate G having such a structure is carried into the chamber 2 from the load lock chamber (not shown) via the substrate carrying-in / out port 36 and is placed on the susceptor 5. In this case, the transfer of the substrate G is performed by a lifter pin (not shown) provided so as to pass through the inside of the susceptor 5 and protrude from the susceptor 5. Next, the substrate G is clamped to the susceptor 5 by the clamp member 6. Thereafter, the gate valve 37 is closed, and the inside of the chamber 2 is evacuated to a predetermined degree of vacuum by the exhaust device 35, and the etching process is started.

This etching process includes a step of removing a surface-altered layer for removing Ti oxide on the surface of the upper Ti film 48, an SD etching step of forming a source electrode and a drain electrode, a step of confirming stop or remarkable deceleration of SD etching, and A channel etching step of etching a semiconductor layer to form a channel portion is sequentially performed. Hereinafter, these steps will be described with reference to the cross-sectional view of FIG.

In the “surface altered layer removing step”, BC
opening the valve 32 of l ₃ source 27, while controlling a predetermined amount of flow by the mass flow controller 33 to introduce the BCl ₃ gas is a process gas into the chamber 2 at a predetermined flow rate, the matching unit from the high frequency power source 14 13 The high frequency power is applied to the susceptor 5 via the. As a result, a high-frequency electric field is generated between the susceptor 5 as the lower electrode and the shower head 15 as the upper electrode, the processing gas is dissociated and turned into plasma, and the Ti oxide film on the surface of the upper Ti film is removed. Thereafter, the high frequency power is cut off.

Next, in the “SD etching step”, the valves 3 of the Cl ₂ supply source 22 and the H ₂ supply source 23 are used.
2, and while controlling the flow rate to a predetermined amount by the mass flow controller 33, C
1-containing gas Cl ₂ gas and H-containing gas H
_While introducing _two gases at a predetermined flow rate, high-frequency power is applied to the susceptor 5. As a result, the processing gas is turned into plasma, and the SD etching proceeds.

At this time, since the photoresist layer 49 is sputtered by ions in the plasma, C in the resist and H of the H ₂ gas contained in the processing gas are polymerized, and a polymer film is formed on the surface to be etched. It is formed. This polymer film is considered to have an effect of inhibiting etching, and the polymer film mainly prevents side etching of the Al film 47, and as shown in FIG. Is obtained. At this time, the polymer film is also deposited on the bottom of the etching hole 50. Due to the deposition of the polymer film, the etching stops or significantly slows down during the SD etching (hereinafter, this state is referred to as etching stop). At this time, since the selectivity of the Al film 47 to the Ti film 46 is high in the etching with the mixed gas of the Cl ₂ gas and the H ₂ gas, the Al film 47 is removed at the time when the etching is stopped.

In this case, the bias power from the high-frequency power source 14 is preferably high from the viewpoint of forming a polymer film on the surface to be etched and performing anisotropic etching in order to improve the shape of SD etching. Conventionally, if the bias power by a high-frequency power source is increased in order to improve the shape of SD etching, the etching selectivity deteriorates and the a-Si film 44 is etched, making it difficult to control the etching distribution in the channel portion. However, since the etching gas contains H ₂ gas, which is an H-containing gas, the etching stop can be generated during the SD etching as described above, so that the selectivity is poor. Can also be solved.

At this time, since at least the Al film 47 must be completely etched by SD etching, an etching stop is generated at least in the middle of the Ti film 46. An etching stop may be generated in the middle of the n ⁺ a-Si film 45. From the viewpoint of improving the controllability of the subsequent channel etching, as shown in FIG. 3B, immediately before (the upper surface) of the n ⁺ a-Si film 45.
It is preferable to cause an etching stop.

Control of the position at which such an etching stop occurs can be achieved by controlling the amount of H ₂ gas, which is an H-containing gas. That is, by controlling the amount of the H ₂ gas, the amount of the polymer film formed by the C—H polymerization can be controlled, and thereby, the position where the etching stops or a significant deceleration can be determined. Specifically, for example, the Cl ₂ / H ₂ flow ratio is 1: 1.
Etching stops at the Ti film 46 at the time of 5: 1.
At this time, an etching stop occurred in the n ⁺ a-Si film 45.

It is also possible to control the bias power by adjusting the power supplied from the high frequency power supply 14 to control the C−
The amount of the polymer film formed by the H polymerization can be controlled, and the position where the etching stop occurs can be controlled. The source electrode 51 and the drain electrode 52 are formed by the SD etching as described above. The source electrode 5
The gate insulating film 43 is exposed on the left side of the gate electrode 1 and on the right side of the drain electrode 52 not covered with the photoresist layer 49 (FIG. 3B).

In the above-mentioned SD etching step, a “step of confirming etching stop of SD etching” is performed as appropriate (for example, every 0.1 seconds). This step is performed by detecting the emission spectra of Al and Ti by dispersing the plasma light transmitted through the window 38 by the plasma light detection device 39. That is, when the etching is performed under the condition that the etching stop occurs in the Ti film 46, it is determined that the etching stop has occurred when the emission spectrum of Al decreases, and the etching stop is performed in the n ⁺ a-Si film 45. In the case where etching is performed under the conditions that cause the above, it is determined that the etching stop has occurred when the emission spectrum of Ti decreases. When the plasma light detection device 39 detects the etching stop, the supply of the processing gas is stopped and the high-frequency power is cut off. Then, the inside of the chamber 2 is evacuated to prepare for the next “channel etching step”.

In the next “channel etching step”, n⁺
The Si-based films of the a-Si film 45 and the a-Si film 44 are etched.
Etching is performed under conditions that are easy to chin. In particular,
SF ₆Source 24, HCl source 25 and He source
Open valve 26 and SF₆Gas, HCl gas, He gas
Into the chamber and apply high frequency power.
In addition, etching proceeds with the plasma of these gases.
Let go. Cl instead of HCl gas₂You can use gas
No.

The bias power in the channel etching step is smaller than that in the SD etching step. The reason for reducing the bias power is to prevent a polymer generated by sputtering the photoresist layer 49 from adhering to the surface to be etched and to prevent the surface to be etched from being damaged by ion bombardment. It is. However, even in this case, a bias power that can remove the polymer adhered to the bottom surface of the etching hole 50 in the SD etching process is necessary. Note that a large / small bias power means a large / small ion energy of ions in the plasma with respect to the surface to be etched.

[0032] SF₆F-containing gas such as Si-based film
Etching of Si-based film with high precision
Can be Moreover, AlF_xThe vapor pressure of the cha
Because it is lower than the pressure in the chamber 2 (about 1.33 Pa)
Al film 47 is hardly etched. etching
If a stop occurs in the Ti film 46, this channel
It is necessary to etch the rest of the Ti film 46 by etching
However, Ti is SF₆Using F-containing gas such as
Etching. Also, SF ₆With gas
The reason why both use HCl gas is that the left side of the source electrode 51 is used.
And the gate exposed on the right side of the drain electrode 52.
To prevent the gate insulating film 43 from being etched.
is there.

By performing the channel etching in this manner, the a-Si film 4 is formed as shown in FIG.
Channel part 53 with good controllability by etching to the middle of 4
Can be formed. The end point of the etching at this time is managed based on a previously grasped time, and the etching is stopped when the etching time reaches a predetermined time.

As described above, in the SD etching,
The processing gas contains H ₂ gas as an H-containing gas, and by applying a relatively large bias power, the photoresist layer 49 is sputtered at the time of etching, so that etching can be performed with good shape. In addition, an etching stop can be generated at an appropriate position by the action of H ₂ which is an H-containing gas, and when the etching stop is confirmed, the processing gas containing SF ₆ which is an F-containing gas for channel etching is processed. By switching, the channel portion can be etched with good controllability. As described above, the shape in the SD etching can be improved, and the controllability of the channel etching can be improved. Therefore, it is possible to remarkably increase these process margins.

In the above embodiment, the high frequency power supply 14 is connected to the susceptor 5 serving as the lower electrode, and the high frequency power is supplied to the susceptor 5 therefrom, so that the power for forming the plasma for etching and the bias power are reduced. Although the apparatus supplied from one high-frequency power source 14 is shown, the high-frequency power supplied to the susceptor 5 is dedicated to the bias power, and the plasma for etching is formed by supplying the high-frequency power to the shower head 15 or the upper part of the chamber. Alternatively, a device may be formed in which an antenna is provided on a side and an induction electric field is formed by supplying high-frequency power thereto.

Next, the results of actually performing the above-described SD etching and channel etching will be described. In this etching, an inductively coupled plasma etching apparatus using an antenna was used. The conditions for SD etching and channel etching are as follows.

The flow ratio of Cl ₂ gas to H ₂ gas in the SD etching step was 5: 1, and the flow ratio of SF ₆ gas, HCl gas and He gas in the channel etching step was 1: 1: 1. The bias power density (high-frequency power applied to the susceptor per unit area of the LCD glass substrate), in the SD etching process 0.29 W / cm ^2, in the channel etching process was 0.06 W / cm ^2.

As a result of this etching, in the SD etching, side etching and the like of the Al film did not occur, good shape was exhibited, and etching was stopped in the n ⁺ a-Si film. Even in the channel etching after confirming the etching stop, side etching does not occur in the Al film, and n
^{+ The} a-Si film and the a-Si film were etched with good controllability, and good channel etching was performed.

The present invention is not limited to the above embodiment, but can be variously modified within the scope of the present invention.
For example, in the above embodiment, an example in which the present invention is applied to the case where the source electrode / drain electrode and the channel portion of a thin film transistor of an LCD are formed is shown, and the present invention is not limited to this. The present invention can be applied to all cases where the laminated structure is etched. Also, Al
Although an example in which a three-layered film of Ti-Al-Ti is used as a system-based film and an n ⁺ a-Si film and an a-Si film are used as a Si-based film, a Ti-Al-Ti film is used as an Al-based film. Not limited to three-layer film, pure Al, Al-Si-Cu, Al-C
u, Al-Nd, or a single layer of an Al alloy, or a composite of these and another film other than Ti. The Si-based film may be poly-Si or single-crystal Si in addition to the above. It may be.

In the above embodiment, the processing gas for etching the Al-based film is C-containing gas as C-containing gas.
Although l ₂ was used and H ₂ gas was used as the H-containing gas, other gases may be used. For example, in the SD etching step, HCl, BCl _3, or the like can be used as an additive gas of the Cl-containing gas, and HCl, HBr, or the like can be used as the H-containing gas.

Further, in the above embodiment, the processing gas for etching the Si-based film is SF ₆ , HC
l, He was used, but not limited thereto, other F-containing gas,
For example it may include a CF ₄ or the like.

[0042]

As described above, according to the present invention,
Since the upper Al-based film is etched by the plasma of the processing gas containing the Cl-containing gas and the H-containing gas, the etching of the Al-based film is etched with good shape by the etching action by the Cl-containing gas and the protection action by the H-containing gas. The etching can be stopped or remarkably decelerated at a desired position by the action of the H-containing gas. After confirming this, the Si-based film can be controlled by etching with a processing gas containing an F-containing gas. Can be etched well. Therefore, it becomes possible to significantly increase the process margin when etching the laminated structure of the lower Si-based film and the upper Al-based film, for example, the source electrode / drain electrode and the channel portion of the thin film transistor in the LCD.

[Brief description of the drawings]

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

FIG. 2 is a sectional view showing a layer structure of a substrate applied to the etching method according to one embodiment of the present invention.

FIG. 3 is a sectional view showing a layer structure of a substrate for describing an etching method according to one embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1; Plasma etching apparatus 2; Chamber 5; Susceptor 6; Clamp member 14; High-frequency power supply 15; Shower head 21; Processing gas supply mechanism 22; Cl ₂ supply source 23; H ₂ supply source 24; SF ₆ supply source 25; He source 39; Plasma light detector 44; a-Si film 45; n ⁺ a-Si films 46 and 48; Ti film 47; Al film 50; etching hole 51; source electrode 52; ; Channel section

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat ゛ (Reference) H01L 21/336 F term (Reference) 4M104 AA09 BB01 BB40 CC01 DD66 DD67 FF16 GG09 5F004 BA04 BB13 BB28 CA02 CB02 DA00 DA04 DA11 DA18 DA22 DA29 DA30 DB01 DB02 DB08 DB09 EA14 EB02 5F110 AA16 CC07 DD02 GG02 GG15 HK01 HK03 HK04 HK09 HK16 HK22 QQ04

Claims (12)

[Claims] 1. An etching method for etching a laminated structure of an upper Al-based film and a lower Si-based film, wherein the upper Al-based film is subjected to plasma of a processing gas containing a Cl-containing gas and an H-containing gas. A first step of etching; a second step of confirming stop or significant deceleration of the etching of the first step; and confirming a stop or significant deceleration of the etching of the first step. Si
And a third step of etching the base film. 2. An Si-based film formed on a substrate via a gate electrode and a gate insulating film, and an A-based film formed on the Si-based film.
An etching method for a thin film transistor, comprising: etching a stacked film having an I-based film; using the Al-based film as a source electrode and a drain electrode; and using the Si-based film as a channel portion. A first step of etching with plasma of a processing gas containing a Cl-containing gas and a H-containing gas, a second step of confirming stop or significant deceleration of the etching of the first step, and after confirming stop or significant deceleration of etching. And a third step of etching the Si-based film with a plasma of a processing gas containing an F-containing gas. 3. The etching method according to claim 1, wherein the Al-based film is a three-layer structure film in which a barrier metal is formed on both sides of an Al-containing film. 4. The Si-based film according to claim 1, wherein the n ⁺ -type amorphous Si film is stacked on an amorphous Si film serving as a channel portion. The etching method according to the paragraph. 5. An amorphous Si film formed on a substrate via a gate electrode and a gate insulating film, an n ⁺ -type amorphous Si film formed thereon, and an Al-containing film formed thereon. Etching a laminated film having a three-layer structure film having a barrier metal formed on both sides, and using the three-layer structure film as a source electrode and a drain electrode, and using the amorphous Si film as a channel portion for a thin film transistor. A method of etching at least the three-layer structure film with a plasma of a processing gas containing a Cl-containing gas and a H-containing gas to form a source electrode and a drain electrode; and stopping the etching in the first step. Or a second step of confirming remarkable deceleration, and a process including F-containing gas after stopping etching or recognizing remarkable deceleration. Etching method characterized by comprising a third step of the plasma gas by etching the n ⁺ -type amorphous Si film and an amorphous Si film to form a channel portion. 6. The method according to claim 3, wherein in the first step, etching is stopped or decelerated in a barrier metal or an n ⁺ type amorphous Si film below the three-layer structure film. Item 2. The etching method according to item 1. 7. The method according to claim 1, wherein in the first step, H
7. The etching method according to claim 6, wherein the position of stopping or significantly decelerating the etching is controlled by controlling the amount of the contained gas. 8. The etching method according to claim 6, wherein in the second step, stopping or remarkable deceleration of the etching is confirmed by monitoring a plasma state. 9. The etching method according to claim 1, wherein the etching in the first step is performed with ions having a higher ion energy than the etching in the third step. . 10. The method according to claim 9, wherein the first step is performed under a condition in which a photoresist as an etching mask is sputtered by a plasma of a processing gas containing a Cl-containing gas and an H-containing gas. Etching method. 11. The method according to claim 1, wherein in the first step, etching is performed using Cl ₂ gas as a Cl-containing gas and H ₂ gas as an H-containing gas. The etching method according to the paragraph. 12. The method according to claim 11, wherein the third step is performed by using a sulfur-containing gas containing sulfur.
And F _6, HCl gas and etching method of any one of claims 1 to 11, characterized in that etching is carried out using a He gas.