JP2002190468A - Method for plasma etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem of an end point of dry etching of a second film being unable to be detected by retaining a film quality or a reaction product of a first film, for plasma etching a film of different area to be etched in a reaction chamber in the same manufacturing apparatus. SOLUTION: A method for plasma etching comprises the steps of first and second plasma etching, inert gas purging by using the same apparatus. Thus, an atmosphere in the reaction chamber is stabilized. The final point of the dry etching of the film of different film quality and etching area can be detected.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma etching method, and more particularly to a plasma etching method having a step of cleaning a reaction chamber between a plurality of plasma etching steps.

[0002]

2. Description of the Related Art In a process of forming an electrode pattern of a semiconductor device, various metal thin films are selectively etched. However, when dry etching is performed as shown in FIG. 1, it is inevitable that reaction products of the etching gas and the thin film-coated substrate to be etched adhere to the reaction chamber. When the amount of the deposit is large, the reaction becomes unstable and causes a decrease in the reproducibility of etching. JP-A-6-302565 discloses a method of cleaning a reaction chamber after dry etching of a metal thin film using a chlorine-based or bromine-based gas.

In a semiconductor device production factory, different materials (for example, a metal thin film and an insulating thin film) are used in one dry etching apparatus due to restrictions on the area of a clean room, the number of manufacturing apparatuses, the number of thin film deposition substrates 2, and the like. In some cases, the thin film deposition substrate is etched. In such a case, a thin film having a large area to be etched is etched first, and then a thin film having a small area to be etched is continuously etched. Since the influence of the adhered matter is large, the end point of the etching of the thin film having a small area to be etched cannot be accurately detected, and the thin film deposition substrate becomes defective due to the remaining film. Therefore, when etching a thin film-coated substrate of a different material with one dry etching apparatus, the vacuum of the reaction chamber was once returned to normal pressure, the reaction chamber was cleaned with alcohol or the like, and dummy discharge and dummy etching were performed. Later, different materials were etched by one dry etching apparatus by a method of processing the next thin film deposition substrate.

[0004]

However, when the switching from the metal film to the insulating film is performed as described above,
Cleaning is performed after the pressure in the reaction chamber is temporarily reduced to normal pressure when the process is switched. In order to eliminate the influence of the residual gas used when etching the metal film, the dummy discharge had to be performed for a certain period of time to return the reaction chamber from normal pressure to vacuum again. Since restarting the apparatus requires a warm-up time, there has been a problem that the operating rate of the apparatus is reduced.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and is intended for use in the case of etching patterns having different film qualities or different areas to be etched even if the films are the same in the same manufacturing apparatus. Another object of the present invention is to efficiently remove attached reaction products and improve the operation rate and productivity of the apparatus.

[0006]

According to a first aspect of the present invention, there is provided a plasma etching method in which thin films having different film qualities and etching areas are etched using the same apparatus. A discharge cleaning step and an inert gas purging step are provided between the second plasma etching step to clean the reaction chamber.

According to a second aspect of the present invention, the end of the second plasma etching step is determined by end point detecting means.

According to a third aspect of the present invention, in the plasma etching method, a CF ₄ gas, a Cl ₂ gas, or a BCl ₃ gas is used as a plasma etching gas, and an Ar gas or a He gas is used as an inert gas. Features.

The operation of the above configuration will be described below.

[0010] The plasma etching method of the present invention comprises:
Plasma discharge cleaning is performed using the gas used to form the pattern of the film, and the reaction products attached to the reaction chamber 10 are removed. Then, the reaction products are removed by an inert gas purge and the atmosphere in the reaction chamber 10 is removed. Stabilize. Next, even when dry etching is performed on films having different film qualities and areas to be etched, the end point can be detected.

With the same pattern, a series of pattern formations by etching and cleaning the first film and etching the second film can be performed without returning the vacuum in the reaction chamber 10 to normal pressure. The equipment operation rate is improved and the productivity is increased. Since the discharge cleaning and the inert gas purge are introduced at the time of switching, the accuracy of the end point detection at the time of film etching is improved. In particular, when an active matrix type liquid crystal substrate is manufactured as a liquid crystal display device, it is possible to prevent a line defect or a lighting failure in the liquid crystal display device due to a contact failure.

[0012]

Embodiments of the present invention will be described below.

(Embodiment 1) FIG. 1 is a schematic configuration diagram of a reactive ion etching (hereinafter referred to as RIE) apparatus used for carrying out the present invention. Here, an end point detector 1, a thin film deposition substrate 2, a temperature control mechanism 3, an end point detection window 4, a monochromator 5, a pressure gauge 6, an upper electrode 7, a lower electrode 8, an exhaust port 9, a reaction chamber 10, a gas introduction. Mouth 11, RF power supply 12,
It is a mass flow controller 13. In the reaction chamber 10,
A gas inlet 11 and an exhaust port 9 are provided. A lower electrode 8 is disposed in the reaction chamber 10, and an upper electrode 7 is attached to an upper end of the reaction chamber 10 so as to face the lower electrode 8. The upper electrode 7 has a gas ejection port,
Holes are open in a shower. High frequency power is applied to the lower electrode 8 from the RF power supply 12 via the matching circuit 23, and the upper electrode 7 is grounded. The reaction chamber 1
0, the lower electrode 8 and the upper electrode 7 are temperature-controlled by the temperature control mechanism 3. The thin film deposition substrate 2 is placed on the lower electrode 8, and the end point detection window 4 is used during dry etching.
, The plasma emission is detected by the monochromator 5 and the end point is detected by the end point detector 1. The plurality of gases are controlled by the mass flow controller 13 to have a desired gas flow rate.

FIG. 2 is a sectional view of a thin film-coated substrate 2 with a metal film used in the embodiment of the present invention. Here, the thin film-coated substrate 2
Is a metal thin film having a film thickness of 0.1 on a glass substrate.
A TaN—Ta—TaN laminated film 14 having a thickness of 4 μm and consisting of three layers of tantalum nitride / tantalum / tantalum nitride is formed by a sputtering method. Further, a resist mask pattern A (a pattern for forming a gate electrode or a source electrode) 15 is formed thereon by a photolithography process using a photolithography technique. This pattern is a pattern for forming an electrode, and has a very large area (product of area and thickness) to be removed by etching.

FIG. 3 is a sectional view of the thin film-coated substrate 2 used in the embodiment of the present invention. Here, the thin film deposition substrate 2 to be etched has a Ta-TaN laminated layer (gate electrode) 1
6 is formed thereon, and a Ta ₂ O ₅ film 1 is formed thereon as an insulating structure.
7 is formed by anodic oxidation, and a SiN film 1 is further formed thereon.
8 is formed by the CVD method. Then, a photoresist mask pattern B (a pattern for forming a terminal portion contact hole) 19 is formed thereon by photolithography. This mask pattern is a pattern for a contact hole in a terminal portion, and has a region to be etched much smaller than that of the resist mask pattern A15.

The above-described RI is applied to the thin film-coated substrate 2 shown in FIG.
Using an E apparatus, the resist mask pattern A15 was used as an etching mask, etching was performed using a mixed gas of CF ₄ and O ₂ , and the pressure was 300 mTo.
rr, CF ₄ gas is 450 sccm, O ₂ gas is 50 sccm
cm, RF frequency is 13.56 MHz, RF power is 10
Perform at 00W. The etching time was controlled by the end point detector 1. After the etching, the thin film-coated substrate 2 is carried out of the reaction chamber 10. The products adhering to the inside of the reaction chamber 10 after the etching include reaction products such as tantalum fluoride, decomposition products of resist, and mixtures thereof.

Next, plasma discharge of CF ₄ and O ₂ is performed.
The discharge conditions were a pressure of 300 mTorr, a CF ₄ gas of 450 sccm, an O ₂ gas of 50 sccm, an RF frequency of 13.56 MHz, an RF power of 500 W, and a discharge time of 15 minutes. In this case, in order to prevent discharge damage to the lower electrode 8, a glass substrate 24 serving as a dummy is formed.
Is placed. Thereafter, argon gas purge is performed through the gas inlet 11. As the purge conditions, the pressure is 300 m
Torr, Ar gas 400 sccm, purge time 2
0 minutes.

Next, after unloading the dummy glass substrate 24, FIG.
The thin film deposition substrate 2 is carried into the reaction chamber 10, and the terminal portion forming mask pattern B having a small portion to be etched is small.
Using 19 as an etching mask, etching was performed using a mixed gas of CF ₄ and O ₂ . As etching conditions,
Pressure 300 mTorr, CF ₄ gas 330scc
m, O ₂ gas is 170 sccm, RF frequency is 13.5
6 MHz and RF power were set to 1800W. The end point of the etching can be detected without being affected by the atmosphere after the etching of the thin film-coated substrate 2 shown in FIG.

As described above, the active matrix type thin film-coated substrate 2 manufactured according to the present invention was assembled into a liquid crystal display device and turned on to confirm the display quality. As a result, spot-like line defects did not occur and the display quality was good. Met.

Comparative Example 1 In the first embodiment of the present invention, the plasma discharge cleaning of CF ₄ and O ₂ and the purging of Ar gas were not performed at the time of process switching, and FIGS.
When the thin film deposition substrate 2 is continuously etched,
Since the end point detection is not performed at an appropriate point during the etching of the thin film-coated substrate 2 in FIG. 3, the insulating film partially remains or is affected by the reaction product, thereby causing a contact failure. When liquid crystal display was performed on a liquid crystal substrate, spot-like line defects were generated.

(Embodiment 2) Ti / Al /
Embodiment 2 in which dry etching of a multilayer metal film composed of three layers of Ti and dry etching of a film composed of two layers of SiN / Mo shown in FIG. 5 are continuously performed will be described. Here, shown are a resist mask pattern A (large pattern to be etched and removed) 15, a resist mask pattern B (small pattern to be etched and removed) 19, a Ti—Al—Ti laminated film 20, a Mo film 21,
An SiN film (passivation film) 22.

First, a gate wiring pattern of an active matrix type liquid crystal substrate having an extremely large area to be etched was formed. The gate wiring film is a metal film composed of three layers of Ti / Al / Ti. This Ti / Al / Ti 3
Dry etching of the layer film was performed under the following conditions. Etching conditions are as follows: pressure is 10 mTorr, Cl ₂ gas is 30 mTorr.
Sccm, BCl ₃ gas was 170 sccm, RF frequency was 13.56 MHz, and RF power was 1200 W.
The etching time was controlled by the end point detector 1. After the etching, the thin film-coated substrate 2 is carried out of the reaction chamber 10. The products adhering to the inside of the reaction chamber 10 after the etching include reaction products such as titanium chloride and aluminum chloride, decomposed products of resist, and mixtures thereof.

Next, plasma discharge of Cl ₂ gas and BCl ₃ gas is performed. Pressure is 10 mTorr, Cl ₂ gas is 30
sccm, BCl ₃ gas was 170 sccm, RF frequency was 13.56 MHz, RF power was 1200 W, and discharge time was 15 minutes. In this case, a dummy glass substrate 24 is placed so as not to damage the lower electrode 8 by discharge. Thereafter, a helium gas purge is performed from the gas inlet 11. As the purge conditions, the pressure was 300 mTorr.
The r and He gases were 400 sccm, and the purge time was 20 minutes. When a comparison was made by performing an argon gas purge instead of the helium gas purge, the effect of the purge did not differ between the He gas and the Ar gas. It should be noted that the He gas and Ar gas purge times were both compared for 20 minutes.

Next, using the same manufacturing equipment, as a step of forming a contact hole in an active matrix substrate of a liquid crystal display device, a pattern with an extremely small area to be etched is dry-etched with respect to the SiN / Mo two-layer film. went. As the etching condition, the pressure is 120 mT.
orr, CF ₄ gas is 300 sccm, O ₂ gas is 200
Sccm, RF frequency was 13.56 MHz, and RF power was 1000 W. Etching time is the end point detector 1
Controlled by The end point of the etching can be detected without being affected by the atmosphere after the etching. As described above, in the display of the active matrix type liquid crystal substrate manufactured according to the present invention, no display failure occurred and the display quality was good.

[0025] (Comparative Example 2) Embodiment 2 of the process switching during the Cl ₂ gas and BCl ₃ gas plasma discharge and then without performing a helium gas purge from the gas inlet 11, continuously be etched thin film deposition substrate 2 In the case where the etching was performed, the end point was not detected during the etching of the substrate 2 to be etched shown in FIG. For this reason, the SiN film partially remained or was affected by the reattachment of the reaction product, which caused a contact failure with the Mo electrode. The active matrix type liquid crystal substrate was assembled and a lighting display test was performed. Lighting was partially defective.

(Embodiment 3) A manufacturing method in the case of performing dry etching of a multilayer film will be described below as Embodiment 3 with reference to FIGS.

FIG. 6 is a flowchart of a manufacturing method in which different photoresist patterns of the present invention are used and a plasma discharge of CF ₄ and O ₂ is used for cleaning.
FIG. 7 is a flowchart of a manufacturing method using plasma discharge cleaning and inert gas purge when using different photoresist patterns according to the present invention. The cleaning gas is Cl ₂ and BCl ₃ .

The flowchart of any of the manufacturing methods is as follows.
Plasma discharge was performed using the same type of gas as that used in the plasma dry etching of the first film to remove the residue once, and then an inert gas purge such as Ar or He was performed.

(Embodiment 4) A manufacturing method in which dry etching is performed on a film in which different types of thin films are laminated using the same photoresist pattern as shown in FIG. FIG. 8 is a flowchart of a manufacturing method using the same pattern and using plasma discharge of CF ₄ and O ₂ for cleaning. FIG.
When a different pattern is used, Cl ₂ is used for cleaning.
4 is a flowchart of a manufacturing method using plasma discharge of BCl ₃ and BCl ₃ . FIG. 8 is a flowchart of a manufacturing method in which the same pattern is used for different laminated films, and a plasma discharge of CF ₄ and O ₂ is used for cleaning.

In the flowchart of this manufacturing method, the first
Plasma discharge was performed with the same type of gas as that used in the plasma dry etching of the film of No. 1 to remove the residue once, and then purged with an inert gas such as Ar or He. The thin-film-deposited substrate 2 is kept in the reaction chamber 10 and then continuously with respect to the second film using a gas of a different type from the gas used in the plasma dry etching of the first film. The pattern formation of the laminated film could be performed with the same pattern as the first film.

[0031]

According to the semiconductor manufacturing apparatus of the present invention, it is possible to remove the reaction products in the upper electrode and stabilize the atmosphere in the reaction chamber. Etching of different homogeneous films
Since the reaction can be performed without returning the vacuum in the reaction chamber to normal pressure, the operation rate is improved.

Further, since the discharge cleaning and the inert gas purge are introduced at the time of switching, the accuracy of detecting the end point at the time of etching the insulating film is improved. When an active matrix liquid crystal substrate is manufactured as a semiconductor device, an effect of preventing generation of line defects and lighting failure in a liquid crystal display device due to a contact defect is exerted.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a reactive ion etching (RIE) apparatus showing a first embodiment and a second embodiment of the present invention.

2A and 2B are a cross-sectional view and a pattern diagram (plan view) of a thin-film-coated substrate having a pattern with a large area to be etched used in Embodiment 1 of the present invention.

3A and 3B are a cross-sectional view and a pattern diagram (plan view) of a thin film-coated substrate 2 having a pattern with a small area to be etched, used in the first embodiment of the present invention.

4A and 4B are a cross-sectional view and a pattern diagram (plan view) of a thin film-coated substrate having a pattern with a large area to be etched used in a second embodiment of the present invention.

5A and 5B are a cross-sectional view and a pattern diagram (plan view) of a thin film-coated substrate having a pattern with a small area to be etched used in Embodiment 2 of the present invention.

FIG. 6 is a flowchart of a manufacturing method using a plasma discharge of CF ₄ and O ₂ for cleaning when using different patterns according to the present invention.

FIG. 7 is a flowchart of a manufacturing method using a plasma discharge of Cl ₂ and BCl ₃ for cleaning when using different patterns according to the present invention.

FIG. 8 is a flow chart of a manufacturing method using a plasma discharge of CF ₄ and O 2 for cleaning when the same pattern is used for different laminated films of the present invention.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 end point detector 2 thin film-attached substrate 3 temperature adjustment mechanism 4 end point detection window 5 monochromator 6 pressure gauge 7 upper electrode 8 lower electrode 9 exhaust port 10 reaction chamber 11 gas inlet 12 RF power supply 13 mass flow controller 14 TaN-Ta -TaN multilayer film 15 a resist mask pattern A (to be etched away region large pattern) 16 Ta-TaN laminated film (gate electrode) 17 Ta ₂ O ₅ film 18 SiN film (gate insulating film) 19 a resist mask pattern B (removal to be etched Small area pattern) 20 Ti-Al-Ti laminated film 21 Mo film 22 SiN film (passivation film) 23 Matching circuit 24 Glass plate

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K057 DA01 DD03 DE01 DE04 DE08 DE20 DG07 DG08 DG12 DG13 DM29 DN01 4M104 AA10 BB16 BB32 CC05 DD66 EE03 EE16 FF13 5F004 AA15 BA04 BB13 BB25 BB26 CB02 DA01 DA04 DB11 DA22 DB12

Claims (3)

[Claims] 1. A plasma etching method for etching thin films having different film qualities and etching areas using the same apparatus, comprising:
A plasma etching method comprising providing a discharge cleaning step and an inert gas purging step to clean a reaction chamber. 2. The plasma etching method according to claim 1, wherein the end of the second plasma etching step is determined by an end point detecting means. 3. A plasma etching gas comprising CF _4
3. The plasma etching method according to claim 1, wherein a gas, a Cl ₂ gas, or a BCl ₃ gas is used, and an inert gas and an Ar gas or a He gas are used.