KR20030042529A - Apparatus for Etching using plasma - Google Patents

Abstract

PURPOSE: A plasma etching apparatus is provided to be capable of efficiently controlling the flow of plasma by using a support part. CONSTITUTION: A chamber(200) is used for etching a wafer(900). A support part(204) is installed in the chamber(200) for supporting the wafer(900). A gas supply part(206) is connected to the chamber(200) for supplying etching gas into the chamber(200). An electrode part(202) is spaced more apart than two times of the diameter of the wafer(900) from the wafer(900), wherein the electrode part(202) is supplied with RF(Radio Frequency) power for transforming the etching gas into plasma. Preferably, the support part(204) is supplied with bias power of 500-5000 Watt for uniformly inducing the plasma on the wafer(900).

Description

Plasma Etching Equipment {Apparatus for Etching using plasma}

The present invention relates to a plasma etching apparatus, and more particularly, to an apparatus for etching a processed film formed on a wafer using plasma.

In recent years, with the rapid spread of information media such as computers, semiconductor devices are also rapidly developing. In terms of its function, the semiconductor device is required to operate at a high speed and to have a large storage capacity. In response to such demands, manufacturing techniques have been developed for semiconductor devices to improve the degree of integration, reliability, and response speed.

In addition, as the semiconductor device is highly integrated, the line width of the circuit pattern becomes finer. An example of such a fine pattern processing technique is an etching technique. The etching technique is a technique of etching a predetermined portion of the films formed on the wafer to form the films in a pattern having electrical properties. In addition, recent etching techniques require a design rule of 0.15 μm or less, and thus, plasma is mainly used.

As an example of devices using such a plasma, issued US Pat. No. 5,228,052 (issued Kikuchi et al) discloses an ashing device having two electrodes for forming a plasma, and issued US Pat. No. 5,888,414 (issued Collins et al. .) Discloses a plasma reaction chamber driven by RF energy inductively coupled inside a reactor dome and using an antenna to form a high density plasma for etching the oxide film.

1 is a schematic diagram illustrating a conventional plasma etching apparatus.

Referring to FIG. 1, the etching apparatus includes a chamber 100 for etching a processed film formed on a wafer 900 into a pattern having electrical characteristics. An upper electrode 102 to which RF power is applied is provided above the chamber 100. The upper electrode 102 applies a high voltage to the etching gas provided in the chamber 100 to form a plasma used to etch the film to be processed. In addition, the bottom of the chamber 100 is provided with a wafer 900 and a lower electrode 104 to which a bias power is applied. The lower electrode 104 has a directionality of the plasma when etching is performed so that the plasma can be oriented. You can adjust the behavior of. Although not shown, a vacuum pump for forming the inside of the chamber in a vacuum state, a throttle valve for adjusting the degree of vacuum in the chamber, a gate valve for opening and closing the vacuum line, a gas supply pipe for providing the gas into the chamber, and the like may be used. It is provided.

However, when the 300 mm wafer is processed using the plasma etching apparatus, the plasma at the center portion and the peripheral portion on the wafer has a different density. Therefore, the uniformity of the pattern formed by the said etching falls. This is because the bias power applied to the lower electrode is about 50 to 500 Watt, which makes it difficult to efficiently adjust the behavior of the plasma.

As a method to compensate for this, there is a method of maximizing the generation density of the plasma by applying a high RF power to the upper electrode. However, when the RF power is applied high, the self-bias power may be increased to damage the pattern formed by the etching.

In addition, the gap between the gas providing unit 102 to which RF power is applied and the wafer 900 to which the bias power is applied is relatively shortened. This is due to the expansion of the chamber 100 due to the large diameter wafer 900. Therefore, the plasma density becomes nonuniform due to the acceleration difference according to the relative chamber length of the plasma ions provided on the central portion and the outer portion of the large-curing wafer 900. As a result, a problem arises in that the processed film on the wafer 900 is not formed in a uniform pattern.

Recently, in order to solve the above problem, a plasma etching apparatus capable of controlling plasma density and self bias power has been developed. However, the plasma etching apparatus does not solve the problem because it is a device applying a 200mm wafer.

Therefore, in recent years, the development of an etching apparatus that can be applied to a 300mm wafer is required.

An object of the present invention is to provide a plasma etching apparatus for efficiently adjusting the behavior of plasma when performing etching on a large diameter wafer.

1 is a schematic diagram illustrating a conventional plasma etching apparatus.

2 is a schematic diagram illustrating a plasma etching apparatus according to an embodiment of the present invention.

3 is a flowchart illustrating a process of etching a polysilicon film using the plasma etching apparatus shown in FIG. 2.

FIG. 4 is a diagram for describing a wafer before an etching process illustrated in FIG. 3 is performed.

FIG. 5 is a diagram for describing a wafer after an etching process illustrated in FIG. 3 is performed.

Explanation of symbols on the main parts of the drawings

100, 200: chamber 102, 202: electrode means

104, 204: support means 206: gas supply pipe

208: vacuum pump 210: vacuum line

212 Throttle Valve 214 Gate Valve

216 permanent magnet 900 wafer

902: oxide film 904a: polysilicon film

904b: polysilicon pattern 906: photosensitive film pattern

The present invention for achieving the above object,

A chamber in which a process of etching an object is performed;

Support means installed in the chamber, for supporting the object to be processed:

Gas providing means for providing an etching gas into the chamber: And

And an electrode means to which RF power is applied to form the etching gas into a plasma, and an interval between the electrode means facing the object and the object to be treated is two or more times larger than the diameter of the object. .

As an example, a bias power of 500 to 5000 W is applied to the support means, and a magnetic field forming unit is formed on the outer sidewall of the chamber to form a magnetic field for efficiently adjusting the behavior of the plasma.

Therefore, by uniformly adjusting the behavior of the plasma when performing the etching, it is possible to improve the uniformity of the pattern by the plasma etching. This is because the bias power can be stably applied to prevent the decrease in the directionality and acceleration of the plasma generated due to the expansion of the distance between the workpiece and the electrode means.

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

2 is a schematic diagram illustrating an etching apparatus using plasma according to an embodiment of the present invention.

Referring to FIG. 2, a plasma etching chamber 200 to which a 300 mm wafer 900 may be applied is shown. In the chamber 200, an upper electrode 202 provided with RF power for forming a gas provided into the chamber 200 in a plasma state is provided thereon. In addition, a gas supply pipe 206 for providing the gas is connected to one side of the chamber 200. The lower electrode 204 on which the wafer 900 is placed is located at the bottom of the chamber 200 and provided to face the upper electrode 202. A vacuum pump 208 is formed at one side of the bottom of the chamber 200 to form a vacuum inside the chamber 200 and to discharge reaction by-products and unreacted gas generated during the etching process. In addition, the vacuum line 210 connecting the chamber 200 and the vacuum pump 208 has a gate that opens and closes according to the operation of the throttle valve 212 and the vacuum pump 208 for adjusting the degree of vacuum inside the chamber 200. Valve 214 is provided.

After the wafer 900 is transferred into the chamber 200 by a transfer robot (not shown) and then loaded into the lower electrode 204, the inside of the chamber 200 may be in a high vacuum state by the operation of the vacuum pump 208. Is formed. Thereafter, the gas is provided into the chamber 200 through the gas supply pipe 206, and RF power for forming the gas into the plasma state is applied to the upper electrode 202. When the gas is formed in the plasma state according to the application of the RF power, a bias power for inducing the plasma onto the wafer is applied to the lower electrode 204. At this time, the upper electrode 202 and the lower electrode 204 preferably has a 600 to 900mm spacing (L ₁ ) that is two to three times the wafer diameter (L2). This is to provide a sufficient distance for uniformly providing the plasma formed inside the chamber 200 on the wafer 900, and also provides a sufficient bias power to induce the plasma onto the wafer 900. 204). That is, by increasing the distance L1 between the upper electrode 202 and the lower electrode 202, it is possible to prevent the increase of the self bias power, and accordingly, a bias power of sufficient magnitude can be applied. In addition, the plasma may be uniformly provided on the wafer 900 to improve the uniformity of the pattern by etching. This is applicable to not only 300mm wafer 900, but also 200mm wafers currently in mass production.

The size of the bias power may be variously changed according to the distance L1 between the upper electrode 202 and the lower electrode 204. In the above embodiment, the bias power provided to the plate is a bias power of 500 to 5000 W, which is four times or more than the bias power used in conventional inductive coupled plasma (ICP), electron cyclotron resonance (ECR), and transformer coupled plasma (TCP) sources. It is applied to the lower electrode 204 to be used.

The reason for this is that as the distance between the upper electrode 202 and the lower electrode 204 to which the bias power is applied increases, the acceleration of plasma ions required for etching is relatively decreased. For this reason, high bias power is applied to maintain the acceleration of the plasma ions necessary for the orientation and etching. Therefore, the plasma is uniformly focused on the wafer 900 to improve the uniformity of the pattern by etching.

In addition, the permanent magnet 216 is provided on the outer wall of the chamber 200 to more uniformly etch the processed film on the wafer 900. This causes the permanent magnet 216 to form a magnetic field inside the chamber 200, which prevents plasma ions or electrons from adhering to the inner wall of the chamber 200. As a result, it is possible to prevent a decrease in the plasma ion density provided on the wafer. In the above embodiment, the permanent magnet 216 is used to form a magnetic field inside the chamber 200, but other members may be used to form the magnetic field inside the chamber 200. That is, the case of using an electromagnet that generates a magnetic field by electric energy is included in the spirit of the present invention.

Hereinafter, as an example of using the plasma etching apparatus, the process of etching the polysilicon film formed on the wafer will be described in detail with reference to the accompanying drawings.

3 is a flowchart illustrating a process of etching a polysilicon film using the plasma etching apparatus illustrated in FIG. 2, and FIG. 4 is a diagram illustrating a wafer before the etching process illustrated in FIG. 3 is performed. 5 is a view for explaining a wafer after the etching process illustrated in FIG. 3 is performed.

Referring to Figures 3, 4 and 5 will be described the etching process as follows.

First, the wafer 900 transferred into the chamber by the transfer robot is loaded on the lower electrode by the lifting operation of the lift pin provided in the lower electrode. Here, the oxide film 902 and the polysilicon film 904a are sequentially formed on the wafer 900, and the photosensitive film pattern 906 for forming the polysilicon film 904a in a specific pattern is a polysilicon film 904a. (S100)

Subsequently, a pressure inside the chamber is formed at 0.5 to 3 Torr by a vacuum pump connected to the chamber, and a process atmosphere is maintained in which the temperature inside the chamber is maintained at 400 to 800 ° C.

In addition, Cl ₂ or SF ₃ gas used as an etching gas through a gas supply pipe and a carrier gas provided for the purpose of conveying the etching gas, exhausting unreacted gas and reaction by-products, and adjusting pressure in the chamber. A mixed gas of He or Ar gas is provided into the chamber. In this case, an O ₂ or N ₂ gas may be further provided for improving an etching profile, and hydrogen bromide (HBr) gas may be further provided for anisotropic etching.

RF power is applied to the upper electrode to form the gases in a plasma state, and bias power is applied to the lower electrode to guide the plasma onto the wafer 900. At this time, the bias power is preferably provided about 1000W. Chlorine or fluorine formed in the plasma state is uniformly provided on the wafer due to the sufficient space provided between the upper electrode and the lower electrode, the application of high bias power, and the magnetic field by the permanent magnet (S400).

Chlorine or fluorine in an ion or radical state formed according to the application of the RF power reacts with the polysilicon film 904a exposed by the photoresist pattern 906 on the wafer 900 to etch a specific portion. As a result, a desired polysilicon pattern 904b is formed. At this time, unreacted gas and reaction by-products generated in the reaction are discharged to the outside of the chamber by the operation of the vacuum pump (S500).

After the dry etching process using the plasma is finished, the photoresist pattern 906 on the polysilicon pattern 904b is removed through the ashing process, thereby completing the polysilicon pattern 904b used as an electrode layer of a complete semiconductor device. do.

In addition, the wafer 900 on which the polysilicon pattern 904b is formed is unloaded by a lift pin provided on the lower electrode, and transferred to the outside of the chamber by a transfer robot.

The etching process is not limited to etching to the polysilicon film, and may be easily applied to a deposition using a plasma, a sputtering process, and the like. That is, it is possible to apply all of the processes to form a plasma, and process the wafer using the same, and can be variously modified.

According to the present invention as described above, the plasma etching apparatus includes an electrode means for applying RF power for forming a gas provided in a chamber into a plasma state and a support means for applying a bias power for inducing the plasma onto a wafer. The electrode means and the support means are provided so that a distance is more than twice the diameter of the wafer. In addition, the bias power is provided to 500 to 5000W and includes a permanent magnet.

Therefore, a plasma having a uniform density is provided on the wafer, and the uniformity of the pattern formed by the plasma is improved to improve the reliability of the semiconductor device. In addition, the maintenance cycle of the plasma etching apparatus is extended, and the operation rate of the plasma etching apparatus is improved.

Although described above with reference to a preferred embodiment of the present invention, those skilled in the art various modifications and variations of the present invention without departing from the spirit and scope of the invention described in the claims below I can understand that you can.

Claims (4)

A chamber in which a process of etching an object is performed; Support means installed in the chamber, for supporting the object to be processed: Gas providing means for providing an etching gas into the chamber: And And an electrode means to which RF power for forming the etching gas into plasma is applied, wherein an interval between the electrode means facing the object and the object is two times or more the diameter of the object to be processed. The plasma etching apparatus of claim 1, further comprising a magnetic field forming unit provided at an outer sidewall of the chamber and configured to adjust a behavior of the plasma by forming a magnetic field inside the chamber. The plasma etching apparatus of claim 1, wherein a bias power of 500 to 5,000 W is applied to the support means. The apparatus of claim 1, wherein the chamber etches a wafer of 300 mm or more, which is a workpiece.