KR101179111B1 - Etching method and recording medium - Google Patents

Abstract

An etching method for etching a fluorine-containing carbon film formed on a substrate by plasma includes a first step of etching by a plasma of a processing gas containing oxygen, and a second step of etching by a plasma of a processing gas containing fluorine. Has a step.

Fluorine, plasma, oxygen, etching

Description

Etching Methods and Storage Media {ETCHING METHOD AND RECORDING MEDIUM}

The present invention relates to an etching method for etching a fluorinated carbon film formed on a substrate such as a semiconductor substrate by plasma, and a storage medium storing a program for executing the method.

As a technique for achieving high integration of a semiconductor device, there is a technique of multilayering wiring. In order to take a multilayer wiring structure, adjacent wiring layers are connected by a conductive layer, and regions other than the conductive layer are interlayer insulating films. It is necessary to insulate by. Although many SiO ₂ films have conventionally been used as such interlayer insulating films, in order to reduce the capacitance between wirings from the viewpoint of miniaturization and high speed of semiconductor devices, low dielectric constant of interlayer insulating films has been oriented.

As such a low dielectric constant interlayer insulating film, a fluorine-added carbon film (fluoro carbon film; CF _x film) that is a compound of carbon (C) and fluorine (F) has attracted attention. The fluorine-added carbon film can have a relative dielectric constant of 2.5 or less by selecting the kind of source gas while the relative dielectric constant of the SiO ₂ film is around 4, which is very effective as an interlayer insulating film having a low dielectric constant. In recent years, high-quality films have been continuously obtained by selection of source gas and development of a CVD apparatus that generates plasma at a low electron temperature at a high density, and has reached a stage that can be put into practical use.

On the other hand, as a method of etching a fluorine-added carbon film, the method of plasmaating hydrogen gas and nitrogen gas, and etching by the plasma is known (Materials Research Society Conference Proceedings, Volume V-14, Advanced Metallization Conference in 1998). However, when this method is adopted, hydrogen enters the sidewall portion of the etched fluorinated carbon film, and the hydrogen combines with fluorine in the film to produce hydrogen fluoride, resulting in damage to the film. In the etched recess, a barrier metal film or metal is embedded in the next step, but when hydrogen fluoride is formed, the barrier metal film or the metal is corroded to inflict damage, and consequently, adhesion to these films. This gets worse.

As a technique for solving such a problem, a technique of etching a fluorine-containing carbon film by plasma of a processing gas containing a C _x F _y (x, y is a natural water) gas such as CF ₄ gas has been proposed (Japanese Patent Laid-Open No. 2005-123406). Thereby, etching with little damage to a fluorine-containing carbon film can be performed.

However, when the fluorine-added carbon film is etched with a C _x F _y- containing gas such as CF ₄ gas, there is a problem that the etching selectivity with respect to hard mask layers such as SiN and SiCN used as the etching mask is low, resulting in insufficient processing shapes. .

(Initiation of invention)

This invention is made | formed in view of such a situation, and an object of this invention is to provide the etching method which can etch a fluorine-containing carbon film in favorable process shape, without damaging. It is also an object to provide a storage medium in which a program for executing such a method is stored.

MEANS TO SOLVE THE PROBLEM In order to solve the said subject, from the 1st viewpoint of this invention, the etching method of etching the fluorine-added carbon film formed on the board | substrate by plasma, The 1st step of performing etching by the plasma of the processing gas containing oxygen, An etching method is provided, which has a second step of etching by plasma of a processing gas containing fluorine.

In a second aspect of the present invention, an etching method of etching a structure in which a fluorine-added carbon film, a hard mask layer, and a resist film are laminated in this order on a semiconductor substrate, wherein the hard mask layer is formed by plasma using the resist film as a mask. And a step of removing the resist film by plasma, and a step of etching the fluorinated carbon film by plasma using the hard mask layer as a mask, and the etching of the fluorinated carbon film includes oxygen. A first step of etching by plasma of a gas and a second step of etching by plasma of a processing gas containing fluorine are provided.

In the second aspect, the hard mask layer is made of a Si-based material, and when etching the hard mask layer, plasma of a processing gas containing C _x F _y (x, y is a natural water) gas is used. It is available. Further, after the hard mask layer is etched to the middle, the resist film is removed, and then the hard mask is etched to expose the fluorine-containing carbon film.

In a third aspect of the present invention, as an etching method for etching a fluorinated carbon film of a structure in which a copper wiring layer and a fluorinated carbon film are sequentially formed on a semiconductor substrate, a step of performing a first etching on the fluorinated carbon film through an etching mask. And after the first etching, forming a silicon coating film on the fluorine-containing carbon film to fill the etching portion, and forming an etching mask on the silicon-based coating film, and through the etching mask to the fluorine-containing carbon film. And a step of removing the silicon-based coating film, thereby forming a trench and a hole reaching the position corresponding to the copper wiring layer in the fluorine-added carbon film, and forming the first and the second 2 etching is the 1st step which etches by the plasma of the process gas containing oxygen, and the process containing fluorine It provides an etching method which is characterized by having a second step of performing an etching by the plasma of the switch.

In the third aspect, prior to the formation of the silicon-based coating film, the wettability property between the silicon-based coating film and the adhesion between the silicon-based coating film and the surface of the fluorine-added carbon film after the first etching is improved, and the adhesion therebetween is improved. You may implement the process of apply | coating the wettability improvement surface modifier for making it favorable. In this case, acetone may be used as the wettability improving surface modifier.

Further, in the third aspect, after the trench and the hole are formed, a fluorine desorption inhibiting surface modifier for modifying the surface of the inner wall surface of the fluorine-added carbon film to suppress the fluorine desorption amount You may perform the process of apply | coating. In this case, ethanol or methanol can be used as the fluorine detachment inhibiting surface modifier.

In the third aspect, after the trench and the hole are formed to expose the copper wiring layer, ammonia water may be applied to the surface of the copper wiring layer to remove a natural oxide film on the surface of the copper wiring layer. . In this case, it is preferable that the ammonia concentration of the said ammonia water is 0.25-5 mass%, and it is preferable that the temperature of the said ammonia water is 0-30 degreeC.

In addition, in the third aspect, the trench may be formed by the first etching, and the hole may be formed by the second etching.

In the first to third aspects, a processing gas containing an O ₂ gas may be used as the processing gas containing oxygen used in the first step of etching the fluorine-containing carbon film. A process gas including the O ₂ gas, O ₂ may be used that composed of a gas alone or O ₂ gas and a rare gas. The first step of etching the fluorine-containing carbon film is preferably performed at a pressure of 13.3 Pa (100 mTorr) or less.

As the processing gas containing fluorine used in the second step of etching the fluorine-containing carbon film, it is possible to include C _x F _y (x, y is natural water) gas. In this case, the processing gas containing fluorine may be composed of C _x F _y (x, y is natural water) gas alone or C _x F _y (x, y is natural water) gas and rare gas. In addition, the C _x F _y (x, y is a natural water) gas is CF ₄ gas, C ₂ F ₆ gas, C ₃ F ₆ gas, C ₄ F ₆ gas, C ₃ F ₈ gas, C ₄ F ₈ gas And C ₅ F ₈ gas.

It is preferable to perform the etching of the fluorine-containing carbon film without opening the atmosphere between the first step and the second step (without exposing the substrate to the atmosphere). In this case, the first step and the second step may be performed in the same processing container, the first step and the second step may be performed in different processing containers, and the substrate may not be opened between the processing containers. You may make it convey without.

The etching of the fluorine-containing carbon film may be performed by a capacitively coupled plasma, or may be performed by a plasma formed by microwaves emitted from a planar antenna having a plurality of slots.

In the fourth aspect of the present invention, as a storage medium storing a program operating on a computer and controlling a plasma processing apparatus, the control program is executed such that the etching method of the first to third aspects is performed when executed. A storage medium is provided in which a computer is controlled by the plasma processing apparatus.

According to the present invention, a first step of etching a fluorine-containing carbon film by a plasma of a processing gas containing oxygen, typically a 0 ₂ gas, and a processing gas containing fluorine, typically Since the etching is performed by the second step of etching by the plasma of the processing gas containing C _x F _y (x, y is a natural water) gas, in the first step, the selectivity to the mask is changed by the processing gas containing oxygen. It is possible to improve the shape by performing a high etching, and since the oxygen remaining on the etching surface can be removed at the time of etching in the second step by the etching in the first step, the surface shape after etching can be improved. .

1 is a cross-sectional view showing an example of a plasma processing apparatus capable of performing an etching method according to the present invention.

2 is a flowchart illustrating a process of an etching method according to an embodiment of the present invention.

3 is a cross-sectional view showing a step of the etching method according to the embodiment of the present invention.

Fig. 4 is a plan view showing a cluster tool type processing system in which an etching method according to the present invention can be implemented.

5 is a flowchart showing an example in which the fluorine-added carbon film is used as the Low-k film and the etching method of the present invention is applied to a damascene process.

6 is a cross-sectional view for explaining the flow of FIG. 5.

FIG. 7 is a view showing a state between a silicon based coating film and a fluorine-containing carbon film coated as a sacrificial film after the trench is formed.

8 is a view showing a state in which the wettability improving surface modifier is applied to the surface of the fluorine-containing carbon film, and a state in which a silicon-based coating film is formed thereafter.

9 is a view showing a state between the fluorine-added carbon film and the silicon-based coating film in the case where acetone as the wettability improving surface modifier is not applied or when the coating is applied.

10 is a view showing a state in which a fluorine desorption inhibiting surface modifier is applied to a surface of a fluorine-containing carbon film, and a state in which the surface is modified.

11 is a view showing a TDS profile of fluorine showing the effect of ethanol as a fluorine desorption-inhibiting surface modifier on the fluorine-containing carbon film after the formation of trenches and vias.

It is a figure which shows the state in which the natural oxide film is formed in the surface of Cu wiring layer after forming a trench and a via.

FIG. 13 is a view showing a state in which ammonia water is applied to the surface of the Cu wiring layer when the natural oxide film of FIG. 12 is formed.

It is a figure which shows the TDS of fluorine with or without ammonia treatment.

It is a figure which shows the surface state of the copper plate processed by Cu oxidation, and the surface state when ammonia treatment is performed to this copper plate.

It is sectional drawing which shows the other example of the plasma processing apparatus which can perform the etching method which concerns on this invention.

17 is a diagram illustrating a structure of a planar antenna member used in the plasma processing apparatus of FIG. 16.

FIG. 18 is a plan view illustrating a structure of a shower plate used in the plasma processing apparatus of FIG. 16.

19 is a scanning micrograph showing a cross section of a wafer sample after the etching of the first step of the etching method of the present invention is completed.

20 is a scanning micrograph showing a cross section of a wafer sample after the etching of the second step of the etching method of the present invention is completed.

21 is a scanning micrograph showing a cross section of a wafer sample when the CF _x film is etched with CF ₄ gas.

Fig. 22 is a TDS profile showing the release of F gas when a sample subjected to two-step etching and a sample formed by depositing a CF _x film on a wafer are heated to 400 ° C.

Fig. 23 is a TDS profile showing the release of HF gas when a sample subjected to two-step etching and a sample formed by depositing a CF _x film on a wafer are heated to 400 ° C.

24 is a diagram showing an XPS profile of a CF _x film before etching.

25 is a diagram showing an XPS profile of a CF _x film after etching with CF ₄ gas and Ar gas.

FIG. 26 is a diagram showing an XPS profile of a CF _x film after etching with H ₂ gas and N ₂ gas. FIG.

FIG. 27 is a diagram showing an XPS profile of a CF _x film after etching with O ₂ gas and Ar gas. FIG.

FIG. 28 shows a TDS profile showing the release of F in the course of raising the temperature to 400 ° C. after etching the CF _x film with CF ₄ gas and Ar gas.

FIG. 29 shows a TDS profile showing the release of F in the course of raising the temperature to 400 ° C. after etching the CF _x film with H ₂ gas and N ₂ gas. FIG.

FIG. 30 shows a TDS profile showing the release of F in the course of raising the temperature to 400 ° C. after etching the CF _x film with 0 ₂ gas and Ar gas.

Best Mode for Carrying Out the Invention [

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of this invention is described with reference to an accompanying drawing.

1 is a cross-sectional view showing an example of a plasma processing apparatus capable of performing an etching method according to the present invention. This plasma processing apparatus is of the type which forms a capacitively coupled plasma by a pair of parallel plate electrodes formed to face up and down.

As shown in FIG. 1, this plasma processing apparatus 10 includes a processing chamber 11 formed in a substantially cylindrical shape, and at the bottom thereof, a susceptor supporter (through a insulating plate 13). 14 is disposed, and the susceptor 15 is disposed thereon. The susceptor 15 also serves as a lower electrode, and the wafer W is placed on the upper surface of the susceptor 15 through an electrostatic chuck 20. Reference numeral 16 is a high pass filter (HPF).

Inside the susceptor support 14, a refrigerant chamber 17 through which a cooling medium of a predetermined temperature circulates is formed, whereby the susceptor 15 is adjusted to a desired temperature. An inlet pipe 18 and a discharge pipe 19 are connected to the coolant chamber 17. Then, the processing temperature of the semiconductor wafer W on the susceptor 15 can be controlled by circulating the refrigerant.

The electrostatic chuck 20 has a structure in which the electrodes 22 are disposed between the insulating materials 21, and a DC voltage is applied from the DC power supply 23 to the electrodes 22, whereby the wafer W is electrostatic chuck ( 20) electrostatic adsorption on the phase. The heat trasfer gas made of He gas is supplied to the rear surface of the wafer W through the gas passage 24, and the wafer W is temperature-controlled by the heat transfer gas. At an upper end of the susceptor 15, an annular focus ring 25 is disposed to improve the uniformity of etching so as to surround the wafer W placed on the electrostatic chuck 20. .

The upper electrode 31 is formed above the susceptor 15 in a state of being supported inside the processing chamber 11 via the insulating material 32 to face the susceptor 15. The upper electrode 31 is comprised from the electrode plate 34 which has many discharge port 33, and the electrode support body 35 which supports this electrode plate 34, and has comprised the shower shape.

A gas inlet 36 is formed in the center of the electrode support 35, and a gas supply pipe 37 is connected thereto. The gas supply pipe 37 is connected to the processing gas supply part 40 which supplies a processing gas for plasma processing. In the process gas supply part (40), O ₂ gas as a treatment gas, C _x F _y gas, for example, CF ₄ gas, N and a _second gas, a rare gas, for example, a process gas supply source for example the Ar gas is supplied is formed, These processing gases can be supplied into the processing chamber 11 at a predetermined flow rate.

An exhaust pipe 41 is connected to the bottom of the processing chamber 11, and an exhaust device 45 is connected to the exhaust pipe 41. The exhaust device 45 is provided with a vacuum pump, such as a turbo molecular pump, a pressure control valve, etc., and can set the inside of the processing chamber 11 to predetermined pressure reduction atmosphere. The gate valve 42 is formed in the side wall part of the processing chamber 11.

The upper electrode 31 is connected with a first high frequency power supply 50 for supplying high frequency power for plasma generation through the first matching unit 51. As a frequency of this 1st high frequency power supply 50, the range of about 27-100 MHz is used. In addition, a low pass filter (LPF) 52 is connected to the upper electrode 31. The susceptor 15 serving as the lower electrode is connected to a second high frequency power supply 60 for introducing ions in the plasma through the second matching unit 61. As a frequency of the 2nd high frequency power supply 60, the range of 300 kHz-13.56 MHz is used, for example.

The plasma processing apparatus 10 has a process controller 70 made of a microprocessor (computer) that controls each component, and each component is connected to and controlled by the process controller 70. In addition, the process controller 70 includes a user interface including a keyboard for the operator to perform command input operations and the like for managing the plasma processing apparatus 10, and a display for visualizing and displaying the operation status of the plasma processing apparatus ( 71) is connected.

The process controller 70 also includes a control program for realizing various processes executed in the plasma processing apparatus 10 under the control of the process controller 70, and respective components of the plasma processing apparatus 10 according to processing conditions. Is connected to a program for executing a process, that is, a storage unit 72 in which a recipe is stored. The recipe is stored in the storage medium in the storage unit 72. The storage medium may be a hard disk or a semiconductor memory, or may be portable such as a CD-ROM, a DVD, a flash memory, or the like. In addition, the recipe may be appropriately transmitted from another apparatus via, for example, a dedicated line.

Then, if necessary, an arbitrary recipe is called from the storage unit 72 by the instruction from the user interface 71 and executed by the process controller 70, so that the plasma processing apparatus (under the control of the process controller 70) The desired process in 10) is performed.

Next, the plasma etching method of this embodiment which is implemented in such a plasma processing apparatus will be described with reference to the flowchart of FIG. 2 and the process sectional view of FIG. 3.

First, an etching stopper layer 301 made of SiCN, for example, is formed on the silicon substrate 300 as shown in FIG. A film (CF _x film) 302 is formed to have a thickness of, for example, 270 nm, and a hard mask layer 303 made of Si-containing material, such as SiCN, is formed to have a thickness of, for example, 30 nm, The resist film 304 which consists of KrF resist, for example, is formed in thickness of 400 nm, for example, and the semiconductor wafer W which patterned this resist film 304 by the photolithography process is prepared ( Step 1).

Next, the semiconductor wafer of such a structure is carried into the plasma processing apparatus 10 of FIG. 1, and is mounted on the susceptor 15 (step 2). As shown in Fig. 3B, the development residue 305 remaining by the development process of the photolithography step is subjected to a descum process (step 3). This process uses, for example, Ar gas and O ₂ gas as the processing gas, and flows them, for example, 135 mL / min (sccm) and 65 mL / min (sccm), respectively, so that the pressure in the processing chamber 11 is 1.33 Pa. It is about 10 mTorr and the high frequency electric power applied is set to the upper electrode: 500W, and the lower electrode: 200W, for example.

After such a discompression process, as shown in FIG.3 (c), the hard mask layer 303 is etched to the middle using the resist film 304 as an etching mask (step 4). This treatment uses, for example, N ₂ gas and CF ₄ gas as the processing gas, and these are respectively 20 to 200 mL / min (sccm), for example 30 mL / min, and 60 to 200 mL / min, for example. For example, 90 mL / min (sccm) is flown, the inside of the process chamber 11 is 1.33-13.3 Pa (10-100 mTorr), for example, 6 Pa (45 mTorr), and the high frequency electric power applied is 0.8-1.8 W / Cm 2, for example 1.6 W / cm 2, lower electrode: 0.18 to 0.45 W / cm 2, for example, 0.22 W / cm 2.

And as shown in FIG.3 (d), when the thickness of the hard mask layer 303 becomes about 1/5-1/3 of the original film thickness, etching of the hard mask layer 303 is stopped once. Then, the processing gas is switched to 0 ₂ gas to remove the resist film 304 by ashing (step 5). This ashing treatment flows a flow rate of O ₂ gas at 100 to 500 mL / min (sccm), for example, 300 mL / min (sccm), and provides 0.67 to 6.7 Pa (5 to 50 mTorr), for example, in the processing chamber 11. For example, 1.3 Pa (10 mTorr), and the high frequency power applied is 0.3 to 1.8 W / cm 2, for example, 0.37 W / cm 2, and lower electrode: 0.04 to 0.4 W / cm 2, for example 0.14 W / cm 2. Do it.

After removing the resist film 304 by ashing in this manner, as shown in FIG. 3E, the etching of the hard mask layer 303 is resumed under the same conditions as in Step 4 so that the hard mask layer 303 is removed. Through, the CF _x film 302 is exposed (step 6).

Next, as shown in FIG. 3 (f), as the etching mask, a hard mask layer 303, the etching is performed for the first step of the CF _x film 302 (step 7). This treatment is performed by a gas containing oxygen as the processing gas, typically a gas containing 0 ₂ gas. Although 0 ₂ gas may be sufficient, it is preferable to add Ar gas etc. from a viewpoint of forming a stable plasma. In this case, the flow rate of the O ₂ gas is 40 to 150 mL / min (sccm), for example 65 mL / min (sccm), and the Ar gas is 80 to 300 mL / min (sccm), for example 135 mL / min (sccm). The inside of the processing chamber 11 is a low pressure condition of 13.3 Pa (100 mTorr) or less, preferably 6.7 Pa (50 mTorr) or less, for example, 1.3 Pa (10 mTorr), and the high frequency power to be applied is the upper electrode: 0.4 ˜1.7 W / cm 2, for example, 0.62 W / cm 2 and lower electrode: 0.2 to 0.55 W / cm 2, for example 0.4 W / cm 2, under conditions with few radicals. In this manner, the etching of the first step is performed with a gas containing oxygen, typically a gas containing O ₂ , thereby increasing the selectivity to the hard mask layer 303 made of Si-containing material, thereby improving the etching shape. It can be made favorable. By etching with C _x F _y gas disclosed in Japanese Laid-Open Patent Publication No. 2005-123406, a sufficient selectivity cannot be obtained with respect to Si-containing hard mask layers such as SiCN, SiN, and the like, which are usually used in this kind of technology. Although the property was not enough, sufficient shape can be obtained by etching with a gas containing oxygen in this way.

However, since the etching of this first step is performed with a gas containing oxygen, oxygen remains on the etching surface as it is, and there is a possibility that it will be oxidized when the metal layer is next formed. Therefore, after performing the etching of the first step with a gas containing oxygen, as shown in Fig. 3G, a gas containing fluorine, typically, C _x F _y (x, y is a natural number). The etching of the second step is performed by the gas containing the appearing gas (step 8). In this case, although C _x F _y gas may be used alone, a rare gas such as Ar gas may be added. This second stage etching may be etched to have a thickness so thin as to remove the surface portion in which oxygen remains after the etching of the first stage is completed. _Examples of the gas represented by C _x F _y include CF ₄ gas, C ₂ F ₆ gas, C ₃ F ₆ gas, C ₄ F ₆ gas, C ₃ F ₈ gas, C ₄ F ₈ gas, and C ₅ F ₈ gas. It can be illustrated. As the etching conditions of this time, the gas containing a fluorine-C _x F _y (x, y is a natural number) as a gas, for example, CF ₄ gas, 100 ~ 400mL / min (sccm ), for example, 100mL / min It is supplied at a flow rate of (sccm), the inside of the processing chamber 11 is 0.67 to 5.3 Pa (5 to 40 mTorr), for example, 1.3 Pa (10 mTorr), and the high frequency power to be applied is the upper electrode: 0.4 to 0.9 W / 2 cm <2>, for example, 0.62 W / cm <2>, The bias to a lower electrode is 0-20 W / cm <2>, Preferably it is performed without applying from a viewpoint of preventing damage. As the processing gas, a rare gas such as Ar gas may be further included as the diluent gas.

By the above processes, the etching of the CF _x film 302 is completed. As described above, the etching of the CF _x film 302 is performed in two steps, a first step using a gas containing oxygen and a second step using a gas containing fluorine, so that the selectivity to the mask in the first step is improved. The low damage etching is performed with high shape, and in the second step, a very thin portion rich in oxygen remaining on the etching surface by the oxygen-containing gas is removed by the fluorine-containing gas. It can be made favorable. For this reason, the etching of a CF _x film having both good shape and surface properties can be realized.

In addition, in these processes, it is preferable that the temperature of the susceptor 15 shall be 10-30 degreeC, and it is preferable that the gap between electrodes is about 30-60 mm.

In the above example, although a series of processes were performed in the same process chamber, you may perform one or several processes in another process chamber. Accordingly, the throughput can be increased by reducing the number of times of gas switching or purging. In this case, it is preferable to convey the semiconductor wafer W between the processing chambers without breaking the vacuum. In particular, the etching of the first step and the etching of the second step of the CF _x film 302 are highly necessary.

Thus, a cluster tool type processing system as shown in FIG. 4 is very suitable as a system which conveys and processes a semiconductor wafer W without destroying a vacuum between a some process chamber. This processing system 100 is provided with four processing units 101, 102, 103, and 104, and each of these units 101-104 is provided in four sides of the conveyance chamber 105 which forms a hexagon, respectively. It is formed correspondingly. Loadlock chambers 106 and 107 are formed on the other two sides of the transfer chamber 105, respectively. Carry-in and out chambers 108 are formed on the side opposite to the transfer chamber 105 of these load lock chambers 106 and 107, and on the side opposite to the load-lock chambers 106 and 107 of the carry-in chamber 108, a semiconductor wafer (W); The ports 109, 110, and 111 which attach three carriers C which can accommodate) are formed.

The processing units 101 to 104 and the load lock chambers 106 and 107 are connected to respective sides of the transfer chamber 105 via gate valves G as shown in the same figure, and these are corresponding gates. By opening the valve G, it communicates with the transfer chamber 105, and cuts off from the transfer chamber 105 by closing the corresponding gate valve G. As shown in FIG. In addition, the gate valve G is formed in the part connected to the carrying-in chamber 108 of the load lock chambers 106 and 107, and the load lock chambers 106 and 107 carry in by opening the corresponding gate valve G. It communicates with the exit 108, and isolate | separates from the carry-in / out chamber 108 by closing the corresponding gate valve G. As shown in FIG.

In the conveyance chamber 105, the wafer conveyance apparatus 112 which carries in / out of the semiconductor substrate W is provided with respect to the processing units 101-104 and the load lock chambers 106 and 107. As shown in FIG. The wafer conveying apparatus 112 is provided in the substantially center of the wafer conveyance chamber 105, and the two blades 114a which support the wafer W at the front-end | tip of the rotational / expandable part 113 which can be rotated and expanded, 114b), and these two blades 114a and 114b are attached to the rotation-expansion part 113 so that they may face mutually opposite directions. Moreover, the inside of this conveyance chamber 105 is hold | maintained by predetermined | prescribed vacuum degree.

Three ports 109, 110, and 111 for attaching the carrier C to the loading and unloading chamber 108 are formed with shutters, not shown, respectively. The wafers W are accommodated in these ports 109, 110, and 111. Or the empty carrier C is directly attached, and when attached, the shutter is pulled out so as to communicate with the carry-in / out chamber 108 while preventing the intrusion of outside air. In addition, an alignment chamber 115 is formed on the side of the carry-in / out chamber 108, and alignment of the semiconductor substrate W is performed there.

In the carry-in / out chamber 108, the conveying apparatus 116 which carries out the carrying-in of the wafer W with respect to the carrier C, and carrying-in / out of the semiconductor substrate W with respect to the load lock chambers 106 and 107 is provided, have. This conveying apparatus 116 has a multi-joint arm structure, and can travel on the rail 118 along the arrangement direction of the carrier C, and the wafer W on the hand 117 of the front end is provided. It raises and performs the conveyance.

This processing system 100 has a process controller 130 made up of each component, that is, a microprocessor (computer) that controls each processing unit, a conveying system, a gas supply system, and the like. 130 is connected to and controlled. The user interface 131 and the storage unit 132 are connected to the process controller 130. These process controller 130, the user interface 131, and the storage unit 132 are configured in the same manner as the process controller 70, the user interface 71, and the storage unit 72.

In such a processing system 100, a part of process is performed by any of the process units 101-104, and a remaining process is performed by another 1 or 2 or more processing units. For example, the discom process of step 3, the hard mask film etching process of steps 4 and 6, and the ashing process of step 5 are performed in one processing unit, and the etching process of the first step of the CF _x film is performed in another processing unit. And the etching step of the second step may be performed in another processing unit. In this case, since the conveyance of the semiconductor wafer W is performed by the conveying apparatus 112 in the conveyance chamber 105 hold | maintained in a vacuum, even if a part of process is performed by another process chamber, a semiconductor is not destroyed. The wafer W can be conveyed, and unwanted oxidation of the etching portion and the like can be prevented.

Next, an example in which the etching method of the present invention is applied to a damascene process will be described using a fluorine-containing carbon film as a low dielectric constant interlayer insulating film (Low-k film). FIG. 5 is a flow chart showing such a manufacturing process, and FIG. 6 is a process sectional view showing the flow of FIG.

First, an insulating film 401 is formed on the Si substrate 400, and a Cu wiring layer 403 is formed over the barrier metal layer 402 on the Si substrate 400, and on the insulating film 401 and the Cu wiring layer 403. A stopper layer (for example, a SiN film or a SiC film) 404 is formed, and a fluorinated carbon film 405 as a low-k film is formed thereon, and an amorphous carbon film 406 and a SiCO film 407 are formed thereon. ) And a photoresist film 408 is formed, and a wafer W having a structure in which a pattern for forming trenches is formed on the photoresist film 408 by photolithography (step 201, FIG. 6A). ).

Subsequently, the SiCO film 407 and the amorphous carbon film 406 are etched using the photoresist film 408 as a mask (step 202, FIG. 6B), and then the SiCO film 407 and amorphous carbon film 406 ), The fluorine-added carbon film 405 is etched to form a trench 409 (step 203, Fig. 6 (c)). The etching at this time is performed by the two-step etching of the etching of the first step by the oxygen-containing gas and the etching of the second step by the fluorine-containing gas as described above.

Next, the silicon-based coating film 410 is formed as a sacrificial film by spin coating so as to fill the trench 409 (step 204, Fig. 6 (d)). This silicon coating film is formed as SOG (Spin On Glass) as an organic silicon containing film, for example. The silicon coating film 410 is formed by spin coating and then sintered by baking.

By the way, prior to forming such a silicon-based coating film 410, it is generally applied to apply a PGME or PGMEA as a coating agent for improving the adhesion to the base, the fluorine-containing carbon film 405 is hydrophobic For this reason, even when such PGME or PGMEA is applied, wettability is poor between the fluorinated carbon film 405 and the silicone coating film 410, resulting in poor adhesiveness, and peeling and voids are generated as shown in FIG. 7. . If such peeling or voiding occurs, there is a problem that etching cannot be performed in an accurate shape.

In order to prevent this, as shown in Fig. 8A, the surface of the fluorine-added carbon film 405 is modified to improve wettability with respect to the silicon-based coating film 410 to improve adhesion. It is desirable to apply the wettability improving surface modifier 411. As a result, as shown in Fig. 8B, the surface of the fluorine-containing carbon film 405 becomes the modified surface 405a, and as shown in Fig. 8C, the silicon coating film 410 is formed. At this time, it becomes what has favorable adhesiveness without peeling etc ..

As such a wettability improving surface modifier 411, acetone can be used suitably, for example. Acetone can roughen the surface of the fluorine-containing carbon film 405 suitably, and can improve adhesiveness with the silicone type coating film 410. As such a wettability improving surface modifier 411, lower ketones, such as 2-butanol, can be used besides acetone. As a method of applying the wettability improving surface modifier 411, a spin coating method of supplying a wettability improving surface modifier 411 such as acetone to the wafer surface through the nozzle while rotating the wafer is very suitable, but the wettability improving surface modifier 411 is suitable. The wafer may be immersed in a vessel in which is stored.

In fact, when the effect of acetone as the wettability improving surface modifier 411 was confirmed, when acetone was not applied, as shown in the SEM photograph of Fig. 9 (a), the fluorine-containing carbon film and the silicon-based coating film were When acetone was apply | coated while peeling generate | occur | produced in between, as shown in the SEM photograph of FIG. 9 (b), peeling did not generate | occur | produce.

After application of the silicon-based coating film 410 in step 204, a photoresist film 412 is formed thereon, and a pattern for forming vias is formed by photolithography (step 205, Fig. 6E). ). Next, the fluorine-added carbon film 405 is etched using the photoresist film 412 as a mask to form a via 413 (step 206, FIG. 6 (f)). The etching at this time is performed by the two-step etching of the etching of the first step by the oxygen-containing gas and the etching of the second step by the fluorine-containing gas as described above.

After the etching of the via 413, the silicon-based coating film 410 is removed by wet processing using DHF (for example, 1% hydrofluoric acid), BHF, or the like, and further, dry using C _x F _y- based gas. The stopper layer 404 is etched by dry etching to expose the Cu wiring layer 403 (step 207, Fig. 6 (g)).

Here, the fluorine-depleted carbon film 405 having undergone the above steps increases the amount of fluorine desorbed due to damage caused by dry etching or the like. When the amount of fluorine desorption increases, the adhesiveness with an upper layer may fall in the subsequent thermal process, peeling off, and the barrier metal (Ta, TaN, Ti, etc.) formed after that may corrode and peel.

In order to prevent this, as shown in Fig. 10A, a fluorine desorption surface modifier 415 is applied to the surface of the fluorine-containing carbon film 405 to modify the surface to suppress the fluorine desorption amount. It is desirable to. As a result, as shown in Fig. 10B, the surface of the fluorine-containing carbon film 405 becomes the modified surface 405b, whereby corrosion of the barrier metal formed thereafter and peeling of the upper layer can be effectively prevented. .

This fluorine desorption suppression surface modifier 415 treats free fluorine removal on the surface of the fluorine-containing carbon film 405 subjected to damage by dry etching or the like and the end of the surface to suppress desorption of fluorine. As the organic solvent having high volatility can be used, ethanol or methanol are very suitable. As a coating method of the fluorine removal inhibitor surface modifier 415, the spin coating method of supplying the fluorine removal inhibitor surface modifying agent 415 such as ethanol to the wafer surface through the nozzle while rotating the wafer is very suitable. The wafer may be immersed in a container in which the modifier 415 is stored.

In fact, in order to grasp the effect of ethanol as such a fluorine desorption suppression surface modifying agent 415, as a result of confirming the degassing amount of fluorine by TDS (Thermal Desorption Spectrometry), as shown in FIG. It was confirmed that the amount of detachment was reduced.

On the other hand, when exposed to the oxygen containing atmosphere in the state which the surface of Cu wiring layer 403 exposed in FIG.6 (g), a natural oxide film is formed in the surface. In addition, impurities may be blown into the surface. If the metal is embedded in the via in this state, the electrical resistance of the via increases, and the resistance of the wiring increases.

Conventionally, removal of a natural oxide film is performed by DHF (for example, 1% hydrofluoric acid), BHF, etc., but it damages the fluorine-containing carbon film 405, and there exists a tendency for fluorine desorption to increase. In addition, low damage chemicals have been studied, but are expensive and depending on the components, waste liquid treatment is complicated and expensive.

It has been found that ammonia water treatment is effective to remove the native oxide film or impurities without causing such a problem. Therefore, in the step of FIG. 6G, when the natural oxide film 416 is formed on the surface of the Cu wiring layer 403 as shown in FIG. 12, the Cu wiring layer 403 is shown in FIG. 13. Ammonia water 417 is applied to the surface of the substrate. The ammonia water can remove the native oxide film and impurities of the Cu wiring layer 403 without causing damage to the fluorine-containing carbon film 405. In addition, ammonia water is inexpensive and easy to treat waste liquid.

Reaction of aqueous ammonia and Cu oxide is as follows.

First, ammonia water is in the equilibrium state, and the reaction of the following formula (1) occurs.

_{NH 3 + H 2 0 = NH} 4 + + OH - ... ... (One)

And Cu oxide turns into 1st copper hydroxide (Cu (OH) ₂ ) which is an intermediate product by reaction of the following (2).

^{Cu + 2OH - = Cu (OH} ) 2 ... ... (2)

(Cu (OH) ₂ ) generates complex ions by reaction with excess NH ₃ and the following formula (3).

_{Cu (OH) 2 + 4NH 3} → [Cu (NH 3) 4] 2+ + 2OH -

= [Cu (NH ₃ ) ₄ ] (OH) ₂ . ... (3)

These complex ions are dissolved in water, resulting in a state in which CuO is dissolved.

It is preferable that the ammonia concentration of ammonia water is 0.25-5 mass%. In this range, the above reaction occurs effectively, and it becomes easy to remove the native oxide film of Cu. Moreover, as for processing time, about 1 to 5 minutes are preferable. As for temperature, 0-30 degreeC is preferable. As the coating method of the ammonia water 417, a spin coating method of supplying the ammonia water 417 to the wafer surface through the nozzle while rotating the wafer is very suitable. However, the wafer may be immersed in a container in which the ammonia water 417 is stored. .

In fact, the effect of such ammonia water treatment was confirmed. 14 is a diagram showing a change in TDS with or without ammonia water treatment. As shown in this figure, it was confirmed that the amount of fluorine desorption was reduced by the ammonia water treatment, and the ammonia water treatment did not damage the fluorine-containing carbon film 405. Next, after 1% ammonia water was applied to the copper plate treated with Cu oxidation on the surface and left for 4 minutes, the state of the surface was confirmed. As a result, the state shown in the photograph of FIG. It was confirmed that the Cu oxide film was removed.

As needed, after performing the above process, the barrier metal film 420 is formed in the inner wall of the trench 409 and the via 413, and the trench 409 and the via 413 are further formed by electroplating. Copper 421 is embedded as the wiring metal (step 208, Fig. 6 (h)). After that, the wafer W is heat-treated to anneal the via 413 and the copper 421 embedded in the trench 409, and further, a planarization process by the CMP method is performed (step 209).

As a result, a desired semiconductor device is manufactured.

In the above description, in the damascene process, an example in which a via is formed after the first trench is formed (Trench First, Via Last) is shown. However, a method of forming the trench after the first via is formed (Beer First). , Trench last).

Next, another plasma processing apparatus which can implement the method of the present invention will be described. 16 is a cross-sectional view showing another plasma processing apparatus to which the method of the present invention is applicable. This plasma processing apparatus 200 is configured as an RLSA microwave plasma processing apparatus for generating plasma by introducing microwaves into a processing chamber with a radial line slot antenna (RLSA), which is a planar antenna having a plurality of slots. .

The plasma processing apparatus 200 has a substantially cylindrical grounded processing chamber (processing container) 201 configured to be hermetically, among which a semiconductor wafer W, which is an object to be processed, is etched. In the upper portion of the processing chamber 201, a microwave introduction portion 230 for introducing microwaves into the processing space is formed.

In the processing chamber 201, a susceptor 205 for horizontally supporting the semiconductor wafer W as an object to be processed is supported in a cylindrical shape in the center of the bottom of the processing chamber 201 through an insulating member 204a. It is formed in the state supported by the member 204.

The electrostatic chuck 206 is formed on the upper surface of the susceptor 205. The electrostatic chuck 206 has a structure in which an electrode 207 made of a conductive film is formed inside the insulator 206a, and a direct current voltage is applied from the direct current power source 208 to the electrode 207, thereby providing a wafer ( W) is electrostatically adsorbed on the electrostatic chuck 206.

An annular focus ring 209 is disposed around the electrostatic chuck 206 (semiconductor wafer W) to improve the uniformity of etching.

Inside the susceptor 205, a coolant chamber 212 through which a cooling medium of a predetermined temperature circulates is formed, whereby the susceptor 205 is adjusted to a desired temperature. An inlet pipe 214a and an outlet pipe 214b are connected to the coolant chamber 212. The processing temperature of the semiconductor wafer W on the susceptor 205 can be controlled by circulating the refrigerant. In addition, a heat transfer gas, for example, He gas, is supplied to the back surface of the wafer W through the gas passage 218, and the wafer is temperature-controlled at a predetermined temperature through the heat transfer gas.

In addition, a high frequency bias power supply 220 is electrically connected to the susceptor 205 through a matching unit 219. The high frequency electric power is supplied from the high frequency bias power supply 220 to the susceptor 205 so that ions are attracted to the wafer W side. The high frequency bias power supply 220 outputs high frequency power of the frequency range within the range of 300 kHz-13.56 MHz, for example.

An exhaust pipe 225 is connected to the bottom of the processing chamber 201, and an exhaust device 226 including a vacuum pump is connected to the exhaust pipe 225. The exhaust device 226 includes a vacuum pump such as a turbo molecular pump, a pressure control valve, and the like, and the inside of the processing chamber 201 can be set to a predetermined reduced pressure atmosphere. A gate valve 242 is formed in the sidewall portion of the processing chamber 201.

The upper part of the processing chamber 201 becomes an opening part, and the microwave introduction part 230 can be arrange | positioned airtight so that this opening part may be blocked. The microwave introduction section 230 includes a transmission plate 228, a planar antenna member 231, and a slow wave material 233 in order from the side of the susceptor 205. These are covered by the shield member 234, the push ring 236, and the upper plate 229.

The transmission plate 228 is made of a dielectric and functions as a microwave introduction window through which microwaves are transmitted and introduced into the processing space in the processing chamber 201. The transmission plate 228 is supported in the airtight state by the upper plate 229 provided in the ring shape below the outer periphery of the microwave introduction part 230. As shown in FIG.

The planar antenna member 231 has a disk shape, and is caught by the inner circumferential surface of the shield member 234 at a position above the transmission plate 228. This planar antenna member 231 is made of a conductor, and a plurality of slot holes 232 for emitting electromagnetic waves such as microwaves are formed in a predetermined pattern to form RLSA.

For example, the slot holes 232 form a long groove shape as shown in FIG. 17, and typically, adjacent slot holes 232 are arranged in a “T” shape, and the plurality of slot holes 232 are formed. ) Is arranged in a concentric shape. The length and arrangement interval of the slot holes 232 are determined according to the wavelength λg of the microwaves in the slow wave material 233, and for example, the intervals of the slot holes 232 are arranged to be 1 / 2λg or λg. . In addition, the slot hole 232 may be another shape, such as circular shape and circular arc shape, and the arrangement form is not limited, either.

The slow wave material 233 has a dielectric constant larger than that of vacuum and is formed on the upper surface of the planar antenna member 231. The slow wave material 233 is made of a dielectric material and has a function of adjusting the plasma by shortening the wavelength of the microwaves since the wavelength of the microwaves is increased in vacuum.

A cooling water flow path 234a is formed in the shield member 234, and the cooling water flows therein to cool the shield member 234, the slow wave material 233, the planar antenna 231, and the transmission plate 228. have. In addition, the shield member 234 is grounded.

The opening part 234b is formed in the center of the shield member 234, and the waveguide 237 is connected to this opening part 234b. The microwave generator 239 is connected to the end of the waveguide 237 through a matching circuit 238. Accordingly, microwaves, for example, at a frequency of 2.45 GHz generated by the microwave generator 239 are propagated to the planar antenna member 231 through the waveguide 237. 8.35 GHz, 1.98 GHz, etc. can also be used as a frequency of a microwave.

The waveguide 237 includes a coaxial waveguide 237a having a circular cross-sectional shape extending upward from the opening 234b of the shield member 234, and a mode converter 240 at an upper end of the coaxial waveguide 237a. It has the rectangular waveguide 237b extended in the horizontal direction connected through the. The mode converter 240 between the rectangular waveguide 237b and the coaxial waveguide 237a has a function of converting microwaves propagating in the TE waveguide in the rectangular waveguide 237b into the TEM mode. An inner conductor 241 is extended in the center of the coaxial waveguide 237a, and the inner conductor 241 is connected and fixed to the center of the planar antenna member 231 at the lower end thereof. As a result, the microwaves are efficiently and uniformly radiated to the planar antenna member 231 via the inner conductor 241 of the coaxial waveguide 237a.

Between the susceptor 205 and the microwave introduction section 230 in the processing chamber 201, a shower plate 251 for introducing a processing gas is formed horizontally. As shown in FIG. 18, the shower plate 251 has a gas flow passage 252 formed in a lattice shape and a plurality of gas discharge holes 253 formed in the gas flow passage 252. Between the spaces 252 is a space 254. A gas supply pipe 255 extending outward from the processing chamber 201 is connected to the gas flow passage 252 of the shower plate 251. The gas supply pipe 255 is connected to a processing gas supply unit 260 that supplies a processing gas for plasma processing. The processing gas supply unit 260 is provided with a processing gas supply source for supplying 0 ₂ gas, C _x F _y gas, for example, CF ₄ gas, N ₂ gas, rare gas, for example Ar gas, as the processing gas. These processing gases can be supplied into the processing chamber 201 at a predetermined flow rate.

On the other hand, in the upper position of the shower plate 251 of the processing chamber 201, a ring-shaped plasma gas introduction member 265 is formed along the chamber wall, and the plasma gas introduction member 265 has a plurality of inner circumferences. A gas discharge hole is formed. A pipe 267 for supplying Ar gas as the plasma gas is connected to the plasma gas introducing member 265. The Ar gas introduced into the processing chamber 201 through the pipe 267 and the gas introducing member 265 is converted into plasma by microwaves introduced into the processing chamber 201 through the microwave introducing unit 230. The Ar plasma passes through the space portion 254 of the shower plate 251 to plasma the process gas discharged from the gas discharge hole 253 of the shower plate 251.

This plasma processing apparatus 200 has a process controller 270 made of a microprocessor (computer) that controls each component, and each component is configured to be connected to and controlled by the process controller 270. The user interface 271 and the storage unit 272 are connected to the process controller 270. These process controllers 270, the user interface 271, and the storage unit 272 are the same as the process controller 70, the user interface 71, and the storage unit 72 in the first embodiment. It is composed.

In the plasma processing apparatus configured as described above, the wafer W is loaded into the processing chamber 201, placed on the susceptor 205, and then processed through the pipe 267 and the gas introducing member 265. While introducing Ar gas into the chamber 201, the microwave from the microwave generator 239 is guided to the waveguide 237 via the matching circuit 238, the rectangular waveguide 237b, the mode converter 240, and Pass the coaxial waveguide 237a in sequence and supply it to the planar antenna member 231 through the inner conductor 241, and radiate into the processing chamber 201 through the transmission plate 228 from the slot of the planar antenna member 231. Let's do it. The microwave propagates in the TE mode in the rectangular waveguide 237b, and the microwave in the TE mode is converted into the TEM mode in the mode converter 240, and propagates in the coaxial waveguide 237a toward the planar antenna member 231. Then, microwaves are radiated from the planar antenna member 231 via the transmission plate 228 to the processing chamber 201, and the Ar gas, which is a plasma generation gas, is converted into plasma by the microwaves.

Subsequently, by supplying a predetermined process gas from the process gas supply unit 260 at a predetermined flow rate, it is excited by the Ar plasma that has passed through the space portion 254 of the shower plate 251, and is converted into plasma. Plasma treatment is performed.

The plasma formed at this time is microwaves emitted from the plurality of slot holes 232 of the planar antenna member 231, so that the plasma has a high density of approximately 1 × 10 ¹¹ to 5 × 10 ¹² / cm 3 and a wafer ( In the vicinity of W), a low electron temperature plasma of about 1.5 eV or less is obtained. Thereby, etching with less damage can be performed.

The plasma processing by the plasma processing apparatus 200 can correspond to any of the steps 3 to 8, and can be performed according to the conditions at the time of the plasma processing apparatus 10, but in particular, the C of step 8 _It is well suited for the etching of the second step of the CF _x film 302 using a gas or the like containing a gas represented by _x F _y (x, y is a natural number). Since the etching of this second step only removes a very thin portion of the surface layer of the CF _x film 302 after the etching of the first step, it is desired that the damage to the film is small, but the RLSA microwave plasma has been described above. Likewise, plasma treatment with high plasma density and low electron temperature can achieve a low damage plasma treatment, which is very suitable for such etching.

Next, the experiment which actually applied the etching method of this invention is demonstrated. First, using a 200 mm silicon wafer, a SiCN film as an etching stopper layer is formed on the silicon substrate to a thickness of 10 nm, a CF _x film is formed thereon to a thickness of, for example, 270 nm, and a SiCN film as a hard mask layer is formed thereon. For example, in FIG. 3 (a) in which a thickness of 30 nm is formed, a resist film made of, for example, a KrF resist is formed to a thickness of 400 nm, and the resist film is patterned to a pattern width of about 200 nm by a photolithography process. The wafer shown in FIG. 1 was first subjected to a discom process for removing the development residue by the apparatus shown in FIG. 1. In this step, Ar gas and O ₂ gas are flowed at flow rates of 135 mL / min (sccm) and 65 mL / min (sccm), respectively, so that the pressure in the processing chamber is 1.33 Pa (10 mTorr), and the applied high frequency power is applied to the upper electrode: 500 W and lower electrodes: 200 W, and the gap between the electrodes was set to 55 mm for 10 sec. Subsequently, the SiCN film as a hard mask layer was etched to the middle as a resist film as an etching mask. The etching was performed by flowing 30 mL / min and 90 mL / min (sccm) of N ₂ gas and CF ₄ gas to ₆ Pa (45 mTorr) in the processing chamber, and applying high frequency power to the upper electrode: 500 W and the lower electrode: 100 W. It carried out for 18 sec. With the gap between electrodes being 60 mm, and the hard mask layer was etched to about 1/4 of the original film thickness. Thereafter, the resist film was removed by ashing. Ashing supplies 0 ₂ gas at a flow rate of 300 mL / min (sccm), sets the inside of the processing chamber to 1.3 Pa (10 mTorr), and applies high frequency power at an upper electrode of 300 W and a lower electrode of 250 W. It carried out for 18 sec by making a gap of 55 mm. Thereafter, the remainder of the hard mask layer was etched for 10 sec under the same conditions as described above to expose the CF _x film.

Next, the first step of the CF _x film was etched using the hard mask layer as an etching mask. Here, 0 ₂ gas is supplied at a flow rate of 65 mL / min (sccm) and Ar gas at 135 mL / min (sccm), the process chamber is set to a low pressure condition of 1.3 Pa (10 mTorr), and the high frequency power applied is The electrode was 500W and the lower electrode was 150W, and the gap between the electrodes was set to 55 mm for 12 sec. Subsequently, the etching of the 2nd step was performed. Here, CF ₄ gas is supplied into the process chamber at a flow rate of 100 mL / min (sccm), the inside of the process chamber is 1.3 Pa (10 mTorr), and the high frequency power to be applied is set to the upper electrode: 500 W, 7 sec. Was performed for 60 mm of gaps between electrodes, without applying a bias to an electrode.

The scanning microscope (SEM) photograph of the cross section of the wafer sample when the etching of the 1st step and the etching of the 2nd step is performed on the said conditions became as shown in FIG. 19 and FIG. 20, respectively. Fig. 19 is an etching of lines, and Fig. 20 is an etching of holes. As shown in FIG. 19, it was confirmed that etching of CF _x film | membrane with ₀₂ + Ar gas performed the etching of favorable substantially vertical shape. However, it was also confirmed that oxygen remained on the surface and the surface properties were poor. On the other hand, after etching with 0 ₂ + Ar gas and etching with CF ₄ gas (two-step etching), as shown in FIG. 20, it was confirmed that etching with good shape and surface properties could be performed.

In addition, as a result of etching the CF _x film only with CF ₄ gas for comparison, as shown in FIG. 21, the etching shape became trapezoidal and it was confirmed that the shape was poor.

In addition, the samples etched in two steps and the samples in which the CF _x film was deposited on the wafer were heated to 400 ° C., and the gas components (F gas and HF gas) emission were confirmed by TDS, as shown in FIGS. 22 and 23. The same result was obtained. In these drawings, data of a sample in which a CF _x film is formed on a wafer is described as "No Treat". From these figures, the sample underwent a two-phase etching, it is degassed and is lower than TDS data of CF _x film groups, and confirmed the validity of the second etching step in the present invention.

Next, the CF _x film was etched with (1) CF ₄ + Ar, (2) H ₂ + N ₂ , and (3) O ₂ + Ar, respectively. Here, etching was performed using the microwave plasma processing apparatus of FIG. In (1), flow rate: CF ₄ / Ar = 200/200 mL / min (sccm), microwave power: 2 kW, bias: 250 W, pressure: 0.93 Pa (7 mTorr), susceptor temperature: 30 ° C. as standard conditions, In (2), flow rate: H ₂ / N ₂ = 200/200 mL / min (sccm), microwave power: 2 kW, bias: 250 W, pressure: 2.66 Pa (20 mTorr), susceptor temperature: 30 ° C. as standard conditions. In (3), flow rate: O ₂ / Ar = 500/500 mL / min (sccm), microwave power: 2 kW, susceptor temperature: 30 ° C., and pressures of 106 Pa (800 mTorr) and 5.3 Pa (40 mTorr). Was performed. First, the surface analysis by XPS (X-ray Photoelectron Spectroscopy) was performed about the sample after these etching and the sample before etching. FIG. 24 is an XPS profile of a CF _x film before etching, FIG. 25 is an XPS profile when etched with CF ₄ + Ar in (1), and FIG. 26 is an XPS profile when etched with H ₂ + N ₂ in (2). 27 is an XPS profile when etched with 0 ₂ + Ar in (3). XPS profile, with respect to the default, the carbon (C1s), oxygen (O1s), fluorine (F1s) when indicates with respect to, the H ₂ + N ₂ (2), in addition to these, there is shown with respect to nitrogen (N1s). Table 1 shows the results of the composition analysis from these profiles.

XPS atmic%



C1s
N1s
O1s
F1s
CF ₄ + Ar

45.8
-
1.8
52.4
H ₂ + N ₂

67.2
15.0
6.4
11.4
0 ₂ + Ar

106 Pa
50.5
-
11.3
38.3
0 ₂ + Ar

5.3Pa
48.2
-
10.5
41.3
No etching

51.6
-
0.8
47.6

In the case of etching with CF ₄ + Ar in (1), as shown in comparison with FIG. 24 and FIG. 25, a large change is not seen in the XPS profile, and as shown in Table 1, the composition is such that the amount of F slightly increases. It was confirmed that silver did not change much before etching and the film was kept intact. On the other hand, when etching was performed by H ₂ + N ₂ in (2), as apparent from comparing FIG. 24 with FIG. 26, the XPS profile was greatly changed, and as shown in Table 1, F was extremely reduced, And N was contained and it was confirmed that damage was contained in the film | membrane. In addition, when etching to ₀₂ + Ar of (3) is compared with FIG. 24 and FIG. 27, a clear change is not seen in XPS profile, but it is large in the ratio of C and F as shown in Table 1, Although there was no fluctuation and the film | membrane was maintained soundly, it was confirmed that the amount of oxygen on the surface increased.

Next, the release of F in the process of raising temperature to 400 degreeC with respect to the sample which etched the said (1)-(3) was confirmed by TDS. The result is shown to FIGS. 28-30. 28 is a case where etching is performed with CF ₄ + Ar of (1), FIG. 29 is a case of etching with H ₂ + N ₂ of (2), and FIG. 30 is a case of etching with 0 ₂ + Ar of (3) to be. When performing the CF etching with ₄ + Ar of (1) As shown in these cases, the release of F (which appears as a line of "No Treatment" in the Fig.) Sample not subjected to etching and has no significant change, In the case of etching with H ₂ + N ₂ in (2), the release of F is larger than in the sample without etching, and in the etching with 0 ₂ + Ar in (3), the pressure is 5.3 Pa (40 mTorr). Although the release of F did not change significantly with the sample which was not etched, the release of F was observed when the pressure was 106 Pa (800 mTorr).

As a result of etching with the various gases described above, the CF _x film is subjected to the etching of the second step with the CF ₄ containing gas after the etching of the first step with the 0 ₂ containing gas is performed on the CF _x film. It is thought that no great damage occurred. In consideration of the release of F, in the low pressure region (specifically, 13.3 Pa (100 mTorr or less)) in which etching with ions is more dominant than etching with etching using the 0 ₂ -containing gas in the first step, It was confirmed that it is important.

In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible within the scope of the idea of this invention. For example, in the said embodiment, although the example performed etching with the capacitively coupled plasma formed by the parallel plate type plasma processing apparatus, and the plasma formed by the microwave radiated | emitted from the planar antenna which has several slot, It is not limited to this. In addition, the first stage etching and the second stage etching of the CF _x film may be performed by another plasma source. For example, the first stage may be performed by a parallel planar capacitively coupled plasma, and the second stage may include a plurality of slots. It may be performed by a plasma formed by microwaves radiated from the planar antenna having the?

According to the present invention, since the shape can be etched satisfactorily without damaging the fluorinated carbon film (CF _x film), the Cu _x layer is used as a low dielectric constant interlayer insulating film (Low-k) film. It is especially effective when manufacturing the semiconductor device of the multilayer wiring structure which has etc. by the damascene method.

Claims (25)

An etching method for etching a fluorinated carbon film formed on a substrate by plasma, An etching method comprising a first step of etching with a plasma of a processing gas containing oxygen and a second step of etching with a plasma of a processing gas containing fluorine following the first step. An etching method for etching a structure in which a fluorine-added carbon film, a hard mask layer, and a resist film are laminated in this order on a semiconductor substrate, Etching the hard mask layer by plasma using the resist film as a mask; Removing the resist film by plasma; Etching the fluorine-containing carbon film by plasma using the hard mask layer as a mask; The etching of the fluorine-containing carbon film, An etching method comprising a first step of etching by a plasma of a processing gas containing oxygen and a second step of etching by a plasma of a processing gas containing fluorine. 3. The method of claim 2, The hard mask layer is made of a Si-based material, and when etching the hard mask layer, an etching method using a plasma of a processing gas containing C _x F _y (x, y is natural water) gas. 3. The method of claim 2, After the hard mask layer is etched to the middle, the resist film is removed, and then the hard mask is etched to expose the fluorine-containing carbon film. An etching method for etching a fluorinated carbon film of a structure in which a copper wiring layer and a fluorinated carbon film are sequentially formed on a semiconductor substrate, Performing a first etching on the fluorine-containing carbon film through an etching mask; After the first etching, forming a silicon-based coating film on the fluorine-containing carbon film to fill the etching portion; Forming an etching mask on the silicon coating film, and performing a second etching on the fluorine-containing carbon film through the etching mask; It has a process of removing the said silicone type coating film, As a result, a trench and a hole reaching a position corresponding to the copper wiring layer are formed in the fluorine-containing carbon film, The said 1st and 2nd etching has the 1st step which etches by the plasma of the process gas containing oxygen, and the 2nd step which etches by the plasma of the process gas containing fluorine. The method of claim 5, Prior to forming the silicon-based coating film, a wettability improving surface for improving the wettability between the silicon-based coating film and the adhesion between the silicon-based coating film and the surface of the fluorinated carbon film after the first etching is performed. An etching method comprising the step of applying a modifier. The method of claim 6, Etching method using acetone as the wettability improving surface modifier. The method of claim 5, And a step of applying a fluorine detachment inhibiting surface modifier for modifying the surface of the fluorine-added carbon film to reduce the amount of fluorine detachment after the trench and the hole are formed. 9. The method of claim 8, And the fluorine desorption surface modifying agent is ethanol or methanol. The method of claim 5, And forming a trench and a hole, applying the ammonia water to the surface of the copper wiring layer and removing the native oxide film on the surface of the copper wiring layer after the copper wiring layer is exposed. The method of claim 10, The ammonia concentration of the said ammonia water is 0.25-5 mass%, The etching method. The method of claim 10, The temperature of the said ammonia water is 0-30 degreeC. The method of claim 5, An trench is formed by the first etching, and a hole is formed by the second etching. The method according to claim 1, 2 or 5, The etching processing gas containing oxygen used in the first step of the fluorine-containing carbon film is etched, O ₂ gas processing gas comprising a. The method of claim 14, The processing gas containing the O ₂ gas is an O ₂ gas alone or an O ₂ gas and a rare gas. The method according to claim 1, 2 or 5, The first step of etching the fluorine-containing carbon film is performed at a pressure of 13.3 Pa (100 mTorr) or less. The method according to claim 1, 2 or 5, Treatment gas containing fluorine is used in the second stage of the fluorine-containing carbon film is etched, the etching method including the C _x F _{y (x, y} is a natural number) gas. 18. The method of claim 17, The processing gas containing fluorine used in the second step of etching the fluorine-added carbon film is C _x F _y (x, y is natural water) gas alone or C _x F _y (x, y is natural water) gas and rare gas The etching method which consists of. 18. The method of claim 17, The C _x F _y (x, y is a natural water) gas is CF ₄ gas, C ₂ F ₆ gas, C ₃ F ₆ gas, C ₄ F ₆ gas, C ₃ F ₈ gas, C ₄ F ₈ gas, the etching method consisting of at least one of C ₅ F ₈ gas. The method according to claim 1, 2 or 5, The etching method of the fluorine-containing carbon film is performed without opening the atmosphere between the first step and the second step. 21. The method of claim 20, The first step and the second step are performed in the same processing container. 21. The method of claim 20, The said 1st step and the said 2nd step are performed in another process container, and the etching method conveys a board | substrate between these process containers without air-opening. The method according to claim 1, 2 or 5, The etching of the fluorine-containing carbon film is performed by a capacitively coupled plasma. The method according to claim 1, 2 or 5, The etching of the fluorine-containing carbon film is performed by a plasma formed by microwaves emitted from a planar antenna having a plurality of slots. A storage medium storing a program for operating on a computer and controlling a plasma processing apparatus, wherein the control program is configured so that the computer executes the etching method according to claim 1, 2 or 5 at the time of execution. A storage medium which controls a plasma processing apparatus.

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