KR100776487B1 - Plasma etching method - Google Patents

Abstract

The present invention relates to a plasma etching method, comprising: transferring a substrate on which a mask pattern is formed into a chamber, supplying an etching gas into the chamber, and applying first bias power to a plasma generator to generate plasma ions; The method may include applying a second bias power to the electric field generator to move the plasma ions to the substrate to etch the exposed portion, and gradually increasing the second bias power during the etching step. By gradually increasing the second bias power, the polymer produced by the reaction with the etching gas does not adhere to the sidewall or the bottom surface, and the etching rate is increased to reduce the slope of the sidewall. Therefore, the etch stop due to the adhesion of the polymer or the increase in the contact resistance is prevented, and the shape of the contact hole is good, the metal layer covering is improved.

Description

Plasma Etching Method {Plasma etching method}

1 and 2 is a configuration diagram for explaining an example of a plasma etching apparatus applied to the present invention.

3 is a cross-sectional view illustrating a method of manufacturing an organic light emitting display device to which the present invention is applied.

4A to 4D are cross-sectional views illustrating a plasma etching method according to the present invention.

5 is a graph illustrating a change in bias power according to a change in etching depth or etching time.

<Explanation of symbols for the main parts of the drawings>

11: chamber 12: gas inlet

13: gas outlet 14: plasma generating unit

15: electric field generator 16: first bias power

17: second bias power 18: plasma

10, 21, 31: substrate 22: buffer layer

23: semiconductor layer 24: gate insulating film

25 gate electrode 26 interlayer insulating film

27, 36: contact holes 32 and 33: first and second insulating films

34: mask pattern 35: polymer

The present invention relates to a plasma etching method, and more particularly, to a plasma etching method using an inductively coupled plasma etching apparatus.

In general, a contact hole or a via hole is formed by a dry etching method using plasma in the manufacturing process of a semiconductor device or a light emitting device.

Plasma etching allows electrons and gas molecules accelerated by an induced electric field to be excited in a plasma state and is etched by chemical reactions and physical collisions by the excited plasma ions.

In the case of using such plasma etching, carbon fluoride (CF) gas is generally used as an etching gas in order to increase the etching selectivity between the photoresist film and the lower layer used as the etching mask and to facilitate polymer production. However, during the etching process, since the polymer generated by the gas is attached to the sidewalls and the bottom surface of the etching mask or the insulating layer in a large amount, the etching is terminated or the contact resistance is increased before the etching stop point is detected. That is, the conventional plasma etching method has a limitation in removing the polymer because the bias power for inducing the electric field is constantly applied, and since the etching is performed at a constant etching selectivity, a contact hole or a via hole having a high sidewall slope is formed. do. Therefore, when the metal is deposited in the contact hole or the via hole, poor step coverage may cause voids or poor contact.

Accordingly, an object of the present invention is to provide a plasma etching method that can solve the above disadvantages by gradually increasing the bias power according to the etching depth or the etching time.

According to an aspect of the present invention, there is provided a plasma etching method including transferring a substrate having a mask pattern formed into a chamber, supplying an etching gas into the chamber, and a first bias power to a plasma generator. Applying a second bias power to an electric field generator to cause the plasma ions to move to the substrate to etch the exposed portion, while the etching step is performed. The second bias power is gradually increased.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to those skilled in the art to fully understand the present invention, and may be modified in various forms, and the scope of the present invention is limited to the embodiments described below. no.

1 and 2 is a configuration diagram for explaining an example of the inductively coupled plasma etching apparatus used in the present invention, the gas inlet 12 and the gas outlet 13 is formed in the chamber 11, the chamber 11 ) Is provided with a plasma generator 14 and an electric field generator 15, and the plasma generator 14 and the electric field generator 15 have a first bias power 16 and a second bias power 17. Are applied respectively.

Referring to FIG. 2, the plasma generator 14 may be configured of an inductively coupled coil, and the electric field generator 15 may be configured in a plate form so that the substrate 10 may be mounted. . The first and second bias powers 16 and 17 may be radio frequency power or direct current (DC) power, and are applied through an electrical matching means (not shown), such as a capacitor. Can be.

When the first bias power 16 is applied to the plasma generator 14, an electric field is induced by a current flowing through a coil, and a high density plasma 18 is generated by collision of electrons and gas molecules accelerated by the induced electric field. Is generated. In addition, when the second bias power 17 is applied to the electric field generator 15, an electric field is formed to move the plasma 18 ions toward the substrate 10 along the electric field. Therefore, the plasma density may be adjusted by adjusting the size of the first bias power 16, and the incident energy of plasma ions may be adjusted by adjusting the size of the second bias power 17.

3 is a cross-sectional view illustrating a manufacturing process of an organic light emitting display device to which the present invention is applied, and schematically illustrates a pixel area.

A buffer layer 22 is formed on the substrate 21, and a semiconductor layer 23 providing an active layer is formed on the buffer layer 22. The semiconductor layer 23 provides source and drain regions and channel regions of the thin film transistor. The gate insulating film 24 is formed on the entire upper surface including the semiconductor layer 23, and the gate electrode 25 is formed on the gate insulating film 24 on the semiconductor layer 23. The interlayer insulating layer 26 is formed on the entire upper surface including the gate electrode 25, and the contact hole 27 is exposed to the interlayer insulating layer 26 and the gate insulating layer 24 so that a predetermined portion of the semiconductor layer 23 is exposed. Is formed. Afterwards, on the interlayer insulating layer 26, the light emitting device includes a source and drain electrode (not shown) and a source or drain electrode connected to the semiconductor layer 23 through the contact hole 27, and the lower electrode, the organic thin film layer, and the upper electrode. An element (not shown) is formed.

The plasma etching method of the present invention can be applied to form the contact holes 27 in the interlayer insulating film 26 and the gate insulating film 24 as described above, and reduces the inclination of the sidewalls of the contact holes 27 to cover the metal layer. This is to be improved, and the contact failure is prevented by preventing the polymer from adhering inside the contact hole 27.

4A to 4D are cross-sectional views for describing a plasma etching method according to the present invention, which will be described below with reference to FIGS. 1 and 5.

Referring to FIG. 4A, a first insulating film 23 and a second insulating film 33 are sequentially formed on a substrate 31 on which an active layer or a conductive layer of a semiconductor material is formed, and then predetermined on the second insulating film 33. A mask pattern 34 having a pattern of is formed. The mask pattern 34 may be a material that may serve as a mask during an etching process for forming a contact hole or a predetermined pattern in the first insulating film 23 and the second insulating film 33, for example, a photoresist film, a silicon oxide film, It may be formed of a silicon nitride film or the like, and may be patterned through an exposure and development process.

Referring to FIG. 1, the substrate 31 on which the mask pattern 34 is formed is transferred into the chamber 11 of the plasma etching apparatus and positioned on the electric field generator 15. Inert gas (He, Ar, N, etc.) and etching gas (CF ₄ , CHF ₃ , C ₄ F ₈ , C ₂ HF ₅ , C ₂ F _6, etc.) into the chamber 11 through the gas inlet 12. After supplying the first bias power 16 to the plasma generator 14.

When the first bias power 16 is applied to the plasma generator 14 in an inert gas atmosphere, an electric field is induced by a current flowing through a coil, and a high density is caused by collision of electrons and etching gas molecules accelerated by the induced electric field. Plasma 18 is generated. That is, the etching gas is ionized and excited in the plasma state.

Referring to FIG. 4B, when the second bias power 17 is applied to the electric field generator 15 to induce the electric field, radicals and ions present in the generated plasma 18 are accelerated by the induced electric field. The second insulating film 33 in the portion exposed by the chemical reaction and the physical collision of the plasma 18 ions moving in the direction 31 and vertically incident is etched.

In the initial etching stage (section T1), the second bias power 17 is applied low, so that the loss of the mask pattern 34 is minimized due to the high etching selectivity, and the etching of the second insulating layer 33 is performed at a high speed. To lose. At this time, since the amount of polymer produced by the chemical reaction between the etching gas and the second insulating film 33 is relatively small, etching is performed even with the low second bias power 17.

Referring to FIG. 4C, the second bias power 17 is gradually increased as the etching depth of the second insulating layer 33 or the etching time elapses (section T2). As the etching depth or the etching time of the second insulating layer 33 and the first insulating layer 32 elapses, the polymer 35 generated by the reaction with the etching gas is attached to the side walls and the bottom surface, thereby preventing the etching. By gradually increasing the second bias power 17 to increase the incident energy of the plasma ions, the polymer 35 is removed by sputtering with high energy plasma ions and at the same time the second insulating film 33 and the first insulating film 32 Also increases the etching rate. In addition, as the loss of the mask pattern 34 is increased by the plasma ions having high energy, the sidewall slope of the mask pattern 34 is reduced, and the slope of the sidewalls of the second insulating film 33 and the first insulating film 32 is also reduced. . An etching depth or an etching time of the second insulating layer 33 and the first insulating layer 32 may be detected using an etch stop detection device (EPD) that detects the reaction gas to detect the etch stop.

Referring to FIG. 4D, when the second insulating layer 33 is completely etched and the first insulating layer 32 is etched by a predetermined thickness to enter the second half of the etching (section T3), the second bias power 17 is increased to the maximum. As the flux density of the electric field induced by the second bias power 17 is increased, the incident energy of the plasma ions is maximized, so that the sidewalls and the bottom of the second insulating film 33 and the first insulating film 32 are formed by the high energy plasma ions. The polymer 35 is not attached to the surface, and the loss of the mask pattern 34 is accelerated, so that the sidewall slope of the mask pattern 34 is further reduced. Therefore, the contact hole 36 of the favorable shape which has the side wall inclination of about 60-70 degrees is formed in the 2nd insulating film 33 and the 1st insulating film 32. FIG.

As an example, the pressure inside the chamber 11 is kept constant, for example, in the range of 5 to 20 mTorr, and different types of etching gases are used in the etching steps (sections T1 and T2) and the etching steps (sections T3), respectively. The etching gas used in the etching step (section T3) may be a gas having a higher etching selectivity than the etching gas used in the etching step (sections T1 and T2). As the generation increases, it is important to consider this choice.

In addition, the first bias power 16 may be uniformly applied in the range of about 1 to 3 kw in consideration of the size of the substrate 10, the desired etching speed, and the like. The second bias power 17 may be changed according to the etching depth or the etching time. For example, when etching a thickness of 1 μm, the second bias power 17 may be within 1 kw up to 0.3 μm, 1.5 kw up to 0.3 μm and 0.7 μm, and It can be adjusted so that it may be 1.8-2kw from 0.7 micrometer to 1 micrometer. Alternatively, in the etching step (section 2), about 120 to 150% of the power applied in the etching step (section T1), and about 200% of the power applied in the etching step (section T1) may be applied. have.

As described above, the preferred embodiment of the present invention has been disclosed through the detailed description and the drawings. The terms are used only for the purpose of describing the present invention and are not used to limit the scope of the present invention as defined in the meaning or claims. Therefore, those skilled in the art will understand that various modifications and equivalent other embodiments are possible from this. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

As described above, the present invention minimizes the bias power at the initial stage of etching so that the loss of the mask pattern is minimized and the etching speed is maintained fast. In the middle of etching, the bias power is gradually increased to remove the polymer and to increase the etching rate of the insulating layer by sputtering by high energy plasma ions. And the loss of the mask pattern is increased so that the slope of the side wall is reduced. In the second half of the etching, the bias power is maximized to prevent the adhesion of the polymer and accelerate the loss of the mask pattern to further reduce the inclination of the side wall. Therefore, the etch stop or the increase of the contact resistance due to the adhesion of the polymer is prevented, and the sidewall slope is reduced to improve the layer covering of the metal in the contact hole.

Claims (10)

Transferring the substrate on which the mask pattern is formed into the chamber; Supplying an etching gas into the chamber; Applying a first bias power to the plasma generator to generate plasma ions; And Applying a second bias power to an electric field generating unit to move the plasma ions to the substrate by the electric field so that the exposed portion is etched; And gradually increasing the second bias power to increase the incident energy of the plasma ions during the etching step. The plasma etching method of claim 1, wherein the mask pattern is formed of any one of a photosensitive film, a silicon oxide film, and a silicon nitride film. The plasma etching method of claim 1, wherein the etching gas is at least one selected from the group consisting of CF ₄ , CHF ₃ , C ₄ F ₈ , C ₂ HF _5, and C ₂ F ₆ . The plasma etching method of claim 1, wherein the etching gas further comprises an inert gas. The plasma etching method of claim 1, wherein the etching gas is ionized by the first bias power to generate the plasma ions. delete The plasma etching method of claim 1, wherein the second bias power is increased with the time that the etching proceeds. The plasma etching method of claim 1, wherein the second bias power is increased according to the etching depth. The method of claim 1, wherein the first and second bias powers are either high frequency power or direct current power. The plasma etching method of claim 1, wherein an etching stop point is detected by detecting a reaction gas during the etching process.

Images