JP2000150481A - Etching device and manufacture of semiconductor device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an etching device which can prevent reaction products of etching from being deposited on the sidewall of a reaction chamber. SOLUTION: An etching device 11 with a reaction chamber 1 in which an etching object 5 is housed has a heating means 30 by which the sidewall 32 of the reaction chamber 1 is heated. The sidewall of the reaction chamber 1 is heated to a temperature not lower than the highest boiling point of reaction products. As an etching treatment is practiced while the sidewall is heated, the reaction products of etching do not adhere to the sidewall of the reaction chamber and the deposition of the reaction products can be avoided.

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 for performing an etching process by accommodating an etching target in a reaction chamber 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 is provided on a reaction chamber 1 having a side wall 32, an upper electrode 2 and a lower electrode 3 provided in the reaction chamber 1 so as to face each other, and a peripheral edge on the upper surface side of the lower electrode 3. And a focus ring 4. 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 is provided in the reaction chamber 1.
Further, an exhaust pipe 9 for discharging a process gas and a reaction product is connected.

When etching the surface of a wafer using such an etching apparatus, first, a wafer 5 is placed on the wafer placement surface 3a of the lower electrode 3, and the reaction chamber 1
A high frequency is applied to the upper electrode 2 with the process gas introduced therein, thereby generating 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.

[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-described structure, the reaction product by the etching adheres to the surface of the side wall 32 of the reaction chamber 1 and the number of processed wafers 5 is increased. The deposit a due to the reaction product is formed on the side wall 32. However, at the time of etching, the plasma spreads to the side wall 32 of the reaction chamber 1 and the deposit a
May be easily separated from the side wall 32, and the deposit a may fall on the surface of the wafer 5 during etching. In such a case, the deposit a serves as an etching mask, and an etching residue is left on the surface of the wafer 5.

[0006] Such a deposit is formed by depositing a reaction product having a high boiling point among etching reaction products on a wall surface or the like of a reaction chamber. Examples of such reaction products include WCl ₆ (boiling point 346.7 ° C.), WCl ₅ (boiling point 275.6 ° C.), TiF ₄ (boiling point 284 ° C.), and the like. This 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. When this plug is formed by using the above etching apparatus, first, as shown in FIG.
2 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, if the deposit a on the side wall of the reaction chamber adheres in the etching apparatus,
As shown in FIG. 6A, the deposit a is peeled off on the surface of the wafer during the etch back of the tungsten film. In such a case, the deposit a serves as an etching mask. As a result, the tungsten film 14 is formed on the interlayer insulating film 31.
And the adhesion layer 13 remains as an etching residue. Therefore, when an upper layer wiring (not shown) is formed on the interlayer insulating film 31 after the end of the etch back, FIG.
The etching residue b shown in (B) remains.
This etching residue b causes a short circuit between the upper wirings,
This is a factor that lowers the yield of semiconductor products. this is,
The same applies to the case where the deposit a itself remains on the interlayer insulating film 31, and this deposit a causes a short circuit between the upper wirings.

[0008] 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.

The present invention has been made in consideration of the above prior art, and has an etching apparatus capable of preventing a deposit of a reaction product by etching from adhering to a side wall of a reaction chamber, and a method of manufacturing a semiconductor device using the same. The purpose is to provide.

[0010]

In order to achieve the above object, according to the present invention, in an etching apparatus having a reaction chamber for accommodating an object to be etched, a side wall of the reaction chamber has a highest boiling point among etching reaction products. And a heating means for heating the reaction product having a temperature higher than the boiling point of the reaction product.

According to this configuration, the side wall of the reaction chamber is heated by the heating means provided in the reaction chamber, and the side wall is heated to the boiling point of the reaction product having the highest boiling point among the etching reaction products. As a result, the reaction product at the time of etching does not adhere to the side wall of the reaction chamber, and no deposit of the reaction product is formed.

In a preferred configuration example, an upper electrode and a lower electrode are arranged in the reaction chamber to face each other, the object to be etched is mounted on the lower electrode, and plasma is generated between the upper electrode and the lower electrode to perform etching. It is characterized by performing.

According to this structure, a remarkable effect of preventing reaction products from adhering to the side wall of the reaction chamber in the plasma etching apparatus can be obtained.

Further, in the present invention, there is provided an etching apparatus wherein a semiconductor wafer to be etched in a semiconductor manufacturing process is accommodated in a reaction chamber, and the semiconductor wafer is subjected to an etching process while heating a side wall of the reaction chamber. To provide a method of manufacturing a semiconductor device.

According to this method, in the etching apparatus used in the semiconductor manufacturing process, since the reaction chamber side wall is heated during the etching process, reaction products are prevented from adhering to the reaction chamber side wall. For this reason, poor etching due to the deposition of the reaction product falling on the wafer surface is prevented, and a high-quality and highly reliable semiconductor product can be obtained.

In a preferred application example, the semiconductor manufacturing process includes a step of forming a lower wiring on a semiconductor wafer, a step of forming an interlayer insulating film on the lower wiring, and forming a through hole in the interlayer insulating film. Forming an adhesion layer on the interlayer insulating film covering the inner surface of the through-hole, forming a metal layer on the adhesion layer to fill the through-hole, and placing the through-hole in a reaction chamber of an etching apparatus. Loading a wafer, etching back the metal layer and the adhesion layer in the reaction chamber, forming a metal plug in a through-hole by the etch-back process, and forming an upper wiring over the metal plug. And a step.

According to this structure, the use of the etching apparatus according to the present invention in the etch-back step in the metal plug forming process prevents deposits of reaction products from being formed. The etching residue of the metal layer on the interlayer insulating film is eliminated, and short circuit of the upper wiring due to the etching residue is prevented, and a highly reliable wiring structure can be obtained.

[0018]

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 device 11 is a parallel plate type etching device,
2, an upper electrode 2 and a lower electrode 3 provided in the reaction chamber 1 so as to face each other, and a focus ring provided around a wafer mounting surface 3 a on the upper surface of the lower electrode 3. And 4. 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. The reaction chamber 1 has a gas inlet 8 for introducing a process gas.
Further, an exhaust pipe 9 for discharging a process gas and a reaction product is connected.

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 11 of the present embodiment, a heater 30 is provided in the side wall 32 of the reaction chamber 1. 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.

The wafer 5 is etched by the plasma. During this etching, the heater 30 heats the side wall 32 of the reaction chamber 1. As a result, a reaction product by the etching does not adhere to the surface of the side wall 32.
Therefore, a deposit of the reaction product is not formed, and the deposit does not drop onto the wafer surface. In this case, it is desirable to heat to a temperature higher than the boiling point of the reaction product having the highest boiling point among the etching reaction products. This reliably prevents the formation of deposits due to the adhesion of the reaction products.

The heater 30 may be an electric heater buried in the side wall, or may be a hot water heater or a steam heater. The disposition position may be an outer surface, an inner surface, a ceiling surface, or the like of the side wall. In addition, a halogen lamp, an infrared heater, or the like may be used, and any other type of heating means may be used as long as the side wall 32 of the reaction chamber 1 can be heated. As heating conditions,
For example, when the temperature of the upper electrode 2 is about 70 ° C. and the temperature of the lower electrode 3 is about 25 ° C., the temperature of the side wall 32 of the reaction chamber 1 is set to about 80 ° C.

An application example of the etching apparatus having the heating means on the side wall of the reaction chamber will be further described. FIG.
FIGS. 3 and 3 are sectional process diagrams for explaining an embodiment in which the etching apparatus of the present invention is applied to a method of 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).

The interlayer insulating film 31 is made of, for example, BPSG (Boron-doped Phospho-Silica) formed by a CVD method.
te Glass) film or PSG (Phospho-Silicate Glass)
It is composed of a membrane. Thereafter, by patterning the interlayer insulating film 31, the lower wiring 2 is formed on the interlayer insulating film 31.
2 is formed (Step S)
3).

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, a plasma of the process gas is generated in the reaction chamber 1 and this plasma is supplied to the surface of the wafer 5, whereby the wafer 5 is etched 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).

Then, 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-described method, the tungsten film 14 is etched back, and during this etch back, the reaction chamber side wall is heated, so that a reaction product by the etching is removed from the side wall 3.
2 does not adhere to the surface. Therefore, a deposit of the reaction product is not formed, and the deposit does not drop onto the wafer surface. Therefore, there is no etching residue of the tungsten film due to the fall of the deposit, the short circuit between the upper wirings 15a formed on the interlayer insulating film 31 is prevented, and the yield of semiconductor products is improved.

The etching apparatus of the present invention is not limited to the parallel plate apparatus described in the present embodiment, as long as the etching apparatus accommodates a wafer in a reaction chamber having a side wall and performs etching. EC
The present invention is applicable to other etching apparatuses using R, induction discharge, or helicon waves 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 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.

[0035]

As described above, in the present invention, the heating means provided in the reaction chamber heats the side wall of the reaction chamber to a temperature higher than the boiling point of the reaction product having the highest boiling point among the etching reaction products, Since the etching process is performed in a state where the side wall is heated, a reaction product at the time of etching does not adhere to the side wall of the reaction chamber, and a deposit of the reaction product is not formed. As a result, etching residue due to the fall of the deposit on the wafer surface does not occur, etching reliability is improved, pattern formation with high accuracy can be performed, and the yield of semiconductor products can be 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, 30: heater, 3
1: interlayer insulating film, 32: side wall.

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4K057 DA01 DB08 DB17 DD01 DE01 DE06 DE14 DG14 DM02 DM28 DM39 DN01 5F004 AA15 AA16 BA04 BA14 BA20 CA01 DA04 DA18 DA23 DA25 DA30 DB04 DB06 DB10 EA27 EA28 EB01 EB02 EB03 5F033 JJ03 KK03 NN06 PP06 PP15 QQ08 QQ09 QQ12 QQ21 QQ31 QQ37 RR14 RR15 SS11 XX21 XX31

Claims (4)

[Claims] 1. An etching apparatus having a reaction chamber for accommodating an object to be etched, comprising: heating means for heating a side wall of the reaction chamber to a temperature equal to or higher than a boiling point of a reaction product having a highest boiling point among etching reaction products. An etching apparatus. 2. An upper electrode and a lower electrode are disposed opposite to each other in the reaction chamber, the object to be etched is mounted on the lower electrode, and plasma is generated between the upper electrode and the lower electrode to perform etching. Claim 1 characterized by the following:
3. The etching apparatus according to claim 1. 3. A semiconductor device using an etching apparatus, wherein a semiconductor wafer to be etched in a semiconductor manufacturing process is accommodated in a reaction chamber, and the semiconductor wafer is subjected to an etching process while heating a side wall of the reaction chamber. Manufacturing method. 4. A semiconductor manufacturing process comprising: forming a lower wiring on a semiconductor wafer; forming an interlayer insulating film on the lower wiring; forming a through hole in the interlayer insulating film; Forming an adhesion layer on the interlayer insulating film covering the inner surface of the through hole; forming a metal layer on the adhesion layer to fill the through hole; and loading the wafer into a reaction chamber of an etching apparatus. Etching back the metal layer and the adhesion layer in the reaction chamber; forming a metal plug in the through hole by the etch-back process; and forming an upper wiring covering the metal plug. A method for manufacturing a semiconductor device using the etching apparatus according to claim 3.