JP2000150471A - Etching apparatus and manufacture of semiconductor device utilizing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching apparatus which prevents that a deposited substance of reactive product by the etching is formed on a focus ring and can reduce a program and a method of manufacturing semiconductor device using the same etching apparatus. SOLUTION: In an etching apparatus 11 comprising an upper electrode 2 and a lower electrode 3 provided opposed with each other and a focus ring 4 placing an etching object 5 on this lower electrode 3 and surrounding the etching area 10, a focus ring 4 is formed of SiC. Since the focus ring 4 consisting of SiC is used, even if a reactive product is adhered and deposited to the surface of focus ring 4 in the course of the etching, the focus ring itself consisting of SiC is etched and therefore the deposited substance is simultaneously separated and evacuated. Accordingly, the deposited substance is no longer dropped on the wafer surface not to generate residues of etching. As a result, short-circuiting of wiring resulting from the residue of etching can be prevented, reliability of wiring structure in the fine pattern can be enhanced and manufacturing yield can also be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an etching apparatus and a method for manufacturing a semiconductor device using the same. More specifically, the present invention relates to an etching apparatus provided with a focus ring around an object to be etched and a method for manufacturing a semiconductor device using the same.

[0002]

2. Description of the Related Art Semiconductor devices are required to have higher integration and higher functionality, and the fine processing technology is becoming increasingly important. With such miniaturization of semiconductor devices,
The dimensions of the width of the wiring and the diameter of the contact holes, through holes, etc. are also reduced. In response to such miniaturization of wiring and the like, a metal plug technology that forms a through hole in an interlayer insulating film, fills the through hole with a metal such as tungsten, and then forms an upper aluminum wiring film. Is used. In this case, the tungsten on the insulating film is removed by etching back using a plasma etching apparatus such as a magnetron etcher.

[0005] FIG. 5 is a configuration diagram of a main part of an etching apparatus used in a manufacturing process of a semiconductor device. The etching apparatus 11 includes: a reaction chamber 1; an upper electrode 2 and a lower electrode 3 provided in the reaction chamber 1 so as to face each other;
There is a focus ring 34 provided around the lower surface of the lower electrode 3 with the wafer mounting surface 3a serving as the upper surface as a bottom surface. A coolant passage 6 for cooling gas or the like is formed in the lower electrode 3. The wafer 5 is sucked and held on the wafer mounting surface 3a of the lower electrode 3 by a vacuum chuck or an electrostatic chuck (not shown). A high frequency power supply 7 is connected to the upper electrode 2, and by applying a high frequency, plasma is excited between the upper electrode 2 and the lower electrode 3 to form a plasma region 10. A gas introduction pipe 8 for introducing a process gas and an exhaust pipe 9 for discharging a process gas and a reaction product are connected to the reaction chamber 1.

When the surface of a wafer is etched by using such an etching apparatus, first, the wafer 5 is placed on the wafer placement surface 3a of the lower electrode 3, and the side circumference of the wafer 5 is focused by a focus ring 34. Surround. Thereafter, a high frequency is applied to the upper electrode 2 while the process gas is introduced into the reaction chamber 1, thereby generating a plasma of the process gas in the reaction chamber 1 and supplying the plasma to the wafer surface. Then, the surface of the wafer is etched by the plasma. At this time, since the focus ring 34 is provided so as to surround the side circumference of the wafer 5, the plasma region is formed stably and the plasma is uniformly supplied to the surface of the wafer 5 placed on the lower electrode 3. Thus, uniformity in the wafer surface in the etching can be obtained. Conventionally, such a focus ring 34 is made of alumina or quartz.

[0005]

However, the above-described etching apparatus and the etching process using the same have the following problems. That is, as shown in FIG. 5, in the etching apparatus having the above configuration, the lower electrode 3
When the focus ring 34 is made of alumina, a reaction product by etching adheres to the surface of the focus ring 34, and the focus ring 34 is processed by stacking the number of processed wafers. Deposits are formed on the surface of the substrate by the reaction product. However, at the time of etching, the surface temperature of the focus ring 34 increases due to direct heat received from the plasma or radiant heat from the upper electrode 2 and the side wall of the reaction chamber 1.

For this reason, the deposit tends to peel off from the surface of the focus ring 34, and the deposit may fall on the surface of the wafer during etching. In such a case, the deposit serves as an etching mask, and etching residue remains on the surface of the wafer.

When the material of the focus ring 34 is quartz, plasma is supplied to the focus ring 34 during etching, so that the focus ring 34 is etched to generate O ₂ (oxygen). Since the plug formed in the through hole in the metal plug forming process is made of W (tungsten), the above oxygen is
Etch the tungsten of the plug. This allows
Plug loss increases.

[0008] This point will be described in more detail. Advances in microfabrication technology accompanying the demand for higher integration of semiconductor devices have led to the miniaturization of wiring dimensions and the diameter of through holes such as contact holes, and the lower through holes in the above through holes have conductive properties such as tungsten. A plug using a conductive material is formed. And when this plug is formed using the above etching apparatus,
First, as shown in FIG. 6A, a lower wiring 22 is formed on a substrate 21, and an interlayer insulating film 31 is formed thereon. The adhesion layer 13 and the tungsten film 14 are laminated in a state of being buried in the through hole 12 formed in the interlayer insulating film 31, and thereafter, they are etched back. Then, as shown in FIG. 6B, the adhesion layer 13 and the tungsten film 14 are left only in the through hole 12, and this is
4a.

However, as described above, when the material of the focus ring 34 is alumina in the above etching apparatus, the deposit a is peeled off on the surface of the wafer during the etch back of the tungsten film as shown in FIG. When it falls, this deposit a becomes a mask. As a result, when an upper layer wiring (not shown) is formed on the interlayer insulating film 31 after the end of the etch back, an etching residue b shown in FIG. 6B remains between the upper layer wirings. This etching residue b causes a short circuit between the upper wirings, which causes a reduction in the yield of semiconductor products. This is the sediment a
The same applies to the case where the film itself remains on the interlayer insulating film 31,
The deposit a causes a short circuit between the upper wirings.

In addition, other than the formation of the plug,
For example, if the deposit a drops on the wafer during etching when patterning the wiring, the deposit a causes a short circuit between the wirings.

When the focus ring 34 is made of quartz in the above etching apparatus, plasma is supplied to the focus ring 34 during etching when etching back the tungsten film.
4 is etched to generate O ₂ (oxygen). Since the plug formed in the through hole is made of W (tungsten), the oxygen etches the tungsten of the plug. As a result, the plug loss L increases as shown in FIG. Then, when an upper layer wiring (not shown) is formed on the interlayer insulating film 31 in a later step, the coverage of the upper layer wiring in the through hole deteriorates. The deterioration of the coverage of the upper wiring becomes a factor for lowering the quality of the semiconductor product. On the other hand, if the degree is poor, it will be an open factor, which will reduce the yield of semiconductor products.

The present invention has been made in consideration of the above-mentioned conventional technique, and uses an etching apparatus capable of preventing a deposit of a reaction product by etching from being formed on a focus ring and reducing plug loss, and an apparatus using the same. It is an object to provide a method for manufacturing a semiconductor device.

[0013]

In order to achieve the above-mentioned object, according to the present invention, there is provided an upper electrode and a lower electrode which are arranged to face each other, an object to be etched is placed on the lower electrode, and a focus which surrounds the etching region is provided. In an etching apparatus provided with a ring, the focus ring is S
An etching apparatus characterized by comprising iC is provided.

According to this structure, even if a reaction product adheres and deposits on the surface of the focus ring during the etching, the focus ring itself made of SiC is etched. At this time, the deposit is simultaneously peeled off. Exhausted. Therefore, the deposit does not fall on the wafer surface to cause etching residue.

Further, since oxygen is not generated when the SiC focus ring itself is etched, a metal such as tungsten for forming a plug is not etched in the metal plug forming process. Therefore, the plug loss is reduced, the coverage of the upper layer wiring is improved, and the reliability of the wiring structure is improved.

In a preferred configuration example, plasma is generated between the upper electrode and the lower electrode to form an etching region.

According to this configuration, particularly in a plasma etching apparatus, by forming the focus ring with SiC, it is possible to prevent the deposit of reaction products from adhering and to prevent the plug from being etched due to the generation of oxygen. Remarkably obtained.

According to the present invention, as a method of manufacturing a semiconductor device, a semiconductor wafer having a thin film to be etched is mounted on a lower electrode opposed to an upper electrode, and the semiconductor wafer is placed around the semiconductor wafer mounting portion of the lower electrode. A method of manufacturing a semiconductor device, comprising: etching a thin film formed on a semiconductor wafer using an etching device provided with a focus ring.
A method for manufacturing a semiconductor device using an etching apparatus, comprising: a focus ring comprising:

According to this configuration, in the etching step in the semiconductor manufacturing process, the operation and effect when the above-described etching apparatus of the present invention is used can be obtained. That is, even if a reaction product adheres and deposits on the surface of the focus ring during the etching, the focus ring itself made of SiC is etched, and at this time, the deposit is peeled off and exhausted at the same time. Therefore, the deposit does not fall on the wafer surface to cause etching residue.

Further, since oxygen is not generated when the SiC focus ring itself is etched, a metal such as tungsten for forming a plug is not etched in a metal plug forming process. Therefore, the plug loss is reduced, the coverage of the upper layer wiring is improved, and the reliability of the wiring structure is improved.

In a preferred configuration example, the process of forming the thin film to be etched on the semiconductor wafer includes:
Forming a lower conductive layer on the semiconductor wafer; forming an interlayer insulating film on the lower conductive layer; forming a connection hole in the interlayer insulating film; and covering the inner surface of the connection hole. Forming an adhesion layer on the interlayer insulation film and forming a metal layer on the adhesion layer to fill the connection holes, and etching back the metal layer and the adhesion layer using the etching apparatus. And a step of forming a metal plug in the connection hole by the etch back process, and a step of forming an upper layer wiring covering the metal plug.

According to this structure, in the manufacturing process of a semiconductor device in which a metal plug is formed by burying a metal in a connection hole of an interlayer insulating film, a deposit of an etching reaction product attached on the focus ring is removed from the focus ring. In addition, since the deposit is dropped and adhered to the wafer surface, the metal layer is not left unetched, so that a short circuit between wirings is eliminated, and a highly reliable metal plug structure can be obtained. Also, S
Since oxygen is not generated when the iC focus ring itself is etched, a metal such as tungsten forming a plug is not etched. Therefore, the plug loss is reduced, the coverage of the upper layer wiring is improved, and the reliability of the wiring structure is improved.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a configuration diagram of a main part of an etching apparatus according to an embodiment of the present invention. This etching apparatus is a parallel plate type etching apparatus, and is described in FIG.
The material of the focus ring is different from that of the above etching apparatus, and the other configuration is substantially the same as the configuration of FIG.
That is, the etching apparatus 11 includes a reaction chamber 1, an upper electrode 2 and a lower electrode 3 provided in the reaction chamber 1 so as to face each other, and a wafer mounting surface 3 a which is the upper surface of the lower electrode 3. And a focus ring 4 provided therearound.

In the lower electrode 3, a coolant passage 6 for cooling gas or the like is provided.
Are formed. The wafer 5 is sucked and held on the wafer mounting surface 3a of the lower electrode 3 by a vacuum chuck or an electrostatic chuck (not shown). A high frequency power supply 7 is connected to the upper electrode 2, and by applying a high frequency, plasma is excited between the upper electrode 2 and the lower electrode 3 to form a plasma region 10. The reaction chamber 1 is connected to a gas inlet 8 for introducing a process gas and an exhaust pipe 9 for discharging a process gas and a reaction product.

The reaction chamber 1 is connected to a load lock chamber (not shown), and a wafer is loaded from the load lock chamber into the reaction chamber 1 while maintaining a vacuum state. Such a load lock chamber may be connected to a plurality of reaction chambers in addition to the reaction chamber and configured as a multi-chamber type etching apparatus as a whole, or may be connected to a cassette chamber for holding a wafer. Is also good.

In the etching apparatus of this embodiment, the material of the focus ring 4 is made of SiC. In the etching apparatus having the above configuration, the inside of the reaction chamber 1 is brought into a predetermined reduced pressure state by the exhaust from the exhaust pipe 9,
A process gas is introduced from the
, A plasma of the process gas is generated in the reaction chamber 1. At this time, the plasma region 10 is stably formed between the upper and lower electrodes 2 and 3 by the focus ring 4, and the plasma is uniformly supplied to the wafer 5 placed on the lower electrode 3. Is etched. At the same time, the surface of the focus ring 4 made of SiC is etched. For this reason, even if the deposit of the reaction product adheres to the surface of the focus ring during the etching, the focus ring itself is etched.
At the same time, the deposit is peeled off and exhausted.

When the focus ring itself is etched, oxygen is not generated, so that tungsten forming a plug is not etched. Therefore, a deposit of a reaction product by the etching is not formed on the focus ring, and the tungsten forming the plug is not etched.

An application example of the etching apparatus provided with such a focus ring made of SiC will be further described. 2 and 3 are sectional process diagrams for explaining an embodiment in which the etching apparatus of the present invention is applied to a method for forming a plug made of tungsten, and FIG. 4 is a flowchart thereof. A method of forming a plug made of tungsten using the above etching apparatus will be described below with reference to FIGS.

First, as shown in FIG.
A lower wiring 22 made of polysilicon is formed on the upper surface (Step S1). The lower wiring 22 is formed by CVD
This is performed by patterning a polysilicon film formed by a (Chemical Vapor Deposition) method. Next, an interlayer insulating film 31 is formed on the substrate 21 so as to cover the lower layer wiring 22 (Step S2). This interlayer insulating film 31
Is a BPSG (Boron-
doped Phospho-Silicate Glass) film or PSG (Phos
pho-Silicate Glass) film. Thereafter, by patterning the interlayer insulating film 31, a through hole 12 reaching the lower wiring 22 is formed in the interlayer insulating film 31 (Step S3).

Then, as shown in FIG. 2B, an adhesion layer 13 made of titanium is formed on the interlayer insulating film 31 by a sputtering method so as to cover the inner wall of the through hole 12 (step S4). Thereafter, a tungsten film 14 is formed on the adhesion layer 13 with a thickness exceeding the depth of the through hole 12 (Step S5). As a result, the inside of the through hole 12 is completely filled with the tungsten film 14.

After the above, as shown in FIG. 2C, the surface of the through hole 12 is etched back so that the tungsten film 14 and the adhesion layer 13 are left only inside the through hole 12,
Tungsten film 14 and adhesion layer 1 on interlayer insulating film 31
3 is removed (step S6).

At the time of this etch-back, the etching surface described with reference to FIG.
The substrate 21 (that is, the wafer 5) is placed on the substrate a, and the pressure in the reaction chamber 1 is reduced to a predetermined pressure by exhaustion from the exhaust pipe 9, and then a process gas is introduced at a predetermined flow rate from the gas introduction pipe 8. In this state, a high frequency is applied to the upper electrode 2 from the high frequency power supply 7. As a result, plasma of the process gas is generated in the reaction chamber 1 and supplied to the surface of the wafer 5 surrounded by the focus ring 4, thereby etching the wafer 5 from the surface side.

An example of the etching conditions for the tungsten film 14 and the adhesion layer 13 will be described below. Initial etching conditions for tungsten film 14 (first step) Process gas and flow rate: sulfur hexafluoride (SF ₆ ) = 110 sccm Argon (Ar) = 90 sccm Pressure in etching atmosphere: 37.3 Pa High frequency (13.56 MHz) applied power : 600 W Etching time: 35 seconds Etching conditions for tungsten film 14 (second step) Process gas and flow rate: Sulfur hexafluoride (SF ₆ ) = 80 sccm Argon (Ar) = 40 sccm Pressure in etching atmosphere: 28.0 Pa High frequency (13) .56 MHz) Applied power: 300 W Etching time: until end point detection Over-etching condition of tungsten film 14 (third step) Process gas and flow rate: sulfur hexafluoride (SF ₆ ) = 80 sccm Argon (Ar) = 40 sccm Pressure in etching atmosphere ： 28.0P RF (13.56 MHz) power applied: 300 W Etching time: etching conditions for 30 seconds adhesion layer 13 (fourth step) process gas and flow rate: Chlorine (Cl ₂₎ = 20 sccm nitrogen (N ₂₎ = 200 sccm etching atmosphere pressure within: 5.3 Pa High frequency (13.56 MHz) applied power: 550 W Etching time: 70 seconds However, the above sccm is a standard cubic centimeter /
minutes.

As described above, by leaving the adhesion layer 13 and the tungsten film 14 only in the through hole 12, a metal plug 14a made of tungsten is formed in the through hole 12 via the adhesion layer 13 (step). S7).

Thereafter, as shown in FIG. 3, an aluminum film 15 is formed on the interlayer insulating film 31 by sputtering so as to cover the plug 14a, and the aluminum film 15 is patterned to form an upper wiring 15a made of aluminum.
Is formed (step S8). This allows plug 1
An upper wiring 15a connected to 4a is formed on interlayer insulating film 11 to complete a semiconductor device.

In the above method, the tungsten film 14 is etched back, and at the same time as this etch back, the surface of the focus ring is etched. For this reason, even if a deposit of a reaction product adheres to the surface of the focus ring during the etching, the focus ring itself is etched. At this time, the deposit is simultaneously peeled off and exhausted. Therefore, the reaction product is prevented from remaining on the interlayer insulating film 31. As a result, a short circuit between the upper wirings 15a formed on the interlayer insulating film 31 can be prevented, and the yield of semiconductor products can be improved.

When the focus ring itself is etched, oxygen is not generated, so that tungsten forming a plug is not etched. Therefore, a deposit of a reaction product by etching is not formed on the focus ring, and tungsten forming the plug is not etched. For this reason, the plug loss is reduced, and when the upper wiring 15a is formed on the interlayer insulating film 31 in a later step, the coverage of the upper wiring in the through hole is improved, and the quality of the semiconductor product can be improved.

The etching apparatus of the present invention is not limited to the parallel plate type described in the present embodiment as long as the etching apparatus has a wafer mounting surface of a lower electrode as a bottom surface and a focus ring on a side periphery thereof. For example, the present invention is applicable to other etching apparatuses using a magnetron, an ECR, an induction discharge, or a helicon wave as a plasma source, and similar effects can be obtained.

Further, in the above-described embodiment, the etching method in the case where the above-described etching apparatus is used at the time of etching back the tungsten film in forming the tungsten plug has been described. However, the method of manufacturing a semiconductor device using the etching apparatus of the present invention is not limited to this, and is also applicable to other etching in patterning for wiring formation and through hole formation, and the like.
A similar effect can be obtained.

[0040]

As described above, in the present invention, since a focus ring made of SiC is used, even if a reaction product adheres and deposits on the surface of the focus ring during etching, the focus ring made of SiC is used. Since the ring itself is etched, the deposit is simultaneously peeled off and evacuated at this time. Therefore, the deposit does not fall on the wafer surface to cause etching residue. As a result, a short circuit between the wirings due to the remaining etching is prevented, the reliability of the wiring structure in the fine pattern is increased, and the yield is improved.

Since oxygen is not generated when the SiC focus ring itself is etched, a metal such as tungsten which forms a plug is not etched in the metal plug forming process. Therefore, the plug loss is reduced, the coverage of the upper layer wiring is improved, and the reliability of the wiring structure is improved.

[Brief description of the drawings]

FIG. 1 is a main part configuration diagram of an etching apparatus according to an embodiment of the present invention.

FIGS. 2A, 2B, and 2C are cross-sectional views of a main part of a wafer, showing in order the steps of a method for manufacturing a semiconductor device using the etching apparatus of the present invention.

FIG. 3 is an essential part cross sectional view of the wafer showing a step that follows the step of FIG. 2;

FIG. 4 is a flowchart of a method for manufacturing the semiconductor device of FIGS. 2 and 3;

FIG. 5 is a configuration diagram of a main part of the etching apparatus.

FIG. 6 is an explanatory view of a problem of a conventional metal plug forming process.

[Explanation of symbols]

1: reaction chamber, 2: upper electrode, 3: lower electrode, 4: focus ring, 5: wafer, 6: refrigerant passage, 7: high frequency power supply, 8: gas introduction pipe, 9: exhaust pipe, 10: plasma area, 11: etching apparatus, 12: through hole, 13
Adhesion layer, 14: tungsten film, 15: aluminum film, 21: substrate, 22: lower wiring, 31: interlayer insulating film.

Claims (4)

[Claims] An upper electrode and a lower electrode which are opposed to each other, and an object to be etched is placed on the lower electrode;
An etching apparatus provided with a focus ring surrounding an etching region, wherein the focus ring is made of SiC. 2. The etching apparatus according to claim 1, wherein plasma is generated between the upper electrode and the lower electrode to form an etching region. 3. A semiconductor wafer on which a thin film to be etched is formed is mounted on a lower electrode opposed to an upper electrode, and an etching apparatus is used in which a focus ring is provided around a semiconductor wafer mounting portion of the lower electrode. A method for manufacturing a semiconductor device, comprising: a step of etching a thin film formed on a semiconductor wafer by using the etching apparatus. Method. 4. A process for forming the thin film to be etched on the semiconductor wafer, comprising: forming a lower conductive layer on the semiconductor wafer; forming an interlayer insulating film on the lower conductive layer; Forming a connection hole in the interlayer insulating film; forming an adhesion layer on the interlayer insulation film so as to cover the inner surface of the connection hole; and forming a metal layer on the adhesion layer to fill the connection hole. Etching back the metal layer and the adhesion layer using the etching apparatus; forming a metal plug in the connection hole by the etch-back process; and forming an upper wiring covering the metal plug. Forming a semiconductor device using the etching apparatus according to claim 3.