JP2003100592A - Method and device for forming reflection preventive film and reflection preventive film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming a reflection preventive film capable of realizing a reflection preventive film capable of generating desired reflectivity and extinction coefficient. SOLUTION: A processor 1 is provided with a twin chamber 3 having two chambers. Then, SiH4 gas, N2 O gas and He gas is supplied through a shower head part 40 connected to a high frequency power source R to each chamber 4 in which an Si wafer W is housed so that a reflection preventive film constituted of an SiON film can be formed. Afterwards, while only the N2 O gas is supplied, plasma is formed in the chamber 4, and the oxidization and modification of the reflection preventive film is carried out by an active species. Thus, the composition of the SiON film or the change of the structure can be generated, and the reflectivity and extinction coefficient of the reflection preventive film can be set so as to be desired values.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method and apparatus for forming an antireflection film and an antireflection film, and more specifically, a method for forming an antireflection film having a desired refractive index and extinction coefficient on a substrate, and The present invention relates to an apparatus therefor and an antireflection film effectively formed by such a method for forming an antireflection film.

[0002]

2. Description of the Related Art In recent years, the miniaturization of semiconductor devices has been accelerated, and the line width of metal wiring and the like tends to be extremely thin. Accordingly, in photolithography in the manufacture of semiconductor devices, an antireflection film (ARC; An
ti-Reflective Coating) is often used. The antireflection film has an antireflection function mainly by canceling the phase of the light reflected from the upper surface and the light reflected from the lower surface. However, the exposure wavelength used in lithography, the thickness of the antireflection film, and the optical Depending on the relationship with the characteristics,
It may be difficult to completely eliminate the reflected light due to the phase difference, and in order to compensate for it, the antireflection film is required to have some light absorption characteristics.

This absorption characteristic exhibited by the antireflection film is generally represented by an index called an extinction coefficient. In order to ensure the required performance in lithography, the film thickness of the antireflection film, the refractive index, and the above extinction coefficient are used. It is necessary to manage and control the three physical quantities. As such an antireflection film, for example, an antireflection insulating film (DARC; Dielectric Anti-Reflective Coating) such as a silicon oxynitride film (SiON film).
Etc. As a method for forming this DARC, for example, a film forming gas containing a silane-based gas as a silicon (Si) source and a dinitrogen monoxide (N ₂ O) gas as a nitrogen and oxygen source is used as a Si wafer or the like. Examples of the method include a thermal CVD method of heating a Si wafer while supplying the Si wafer on the substrate, a plasma CVD method, and the like.

[0004]

By the way, the above-mentioned optical characteristics (refractive index and extinction coefficient) required for an antireflection film in lithography are usually the underlayer of the antireflection film (for example, a metal film such as aluminum, It is determined so as to match the optical characteristics of the polysilicon film). On the other hand, the conventional DARC including a SiON film has a constant refractive index and extinction coefficient even if various film forming conditions such as a film forming gas mixture ratio, a film forming pressure, and a film forming temperature are changed. Tends to show a correlation of

That is, in the conventional DARC, it is extremely difficult to change (control) the refractive index and the extinction coefficient independently. Therefore, it is not possible to form an antireflection film that satisfies both the desired refractive index and extinction coefficient required by lithography, and in some cases it may be difficult to obtain the desired line width in patterning the resist film. .

Therefore, the present invention has been made in view of such circumstances, and provides a method for forming an antireflection film and an apparatus therefor capable of realizing an antireflection film exhibiting a desired refractive index and extinction coefficient. The purpose is to provide. Also,
An object of the present invention is to provide an antireflection film that exhibits a desired refractive index and extinction coefficient.

[0007]

In order to solve the above-mentioned problems, the method for forming an antireflection film according to the present invention comprises supplying a first gas (film forming raw material gas) onto a substrate, and then applying the first gas onto the substrate. A film forming step of forming a first antireflection film having a first refractive index and a first extinction coefficient, and a second film containing oxygen atoms in the molecule
Gas (reforming gas) is supplied onto the substrate on which the first antireflection film is formed, and a plasma forming step for forming plasma around the substrate on which the first antireflection film is formed. And a second antireflection film having a second refractive index different from the first refractive index and a second extinction coefficient different from the first extinction coefficient. And a reforming step of reforming into the prevention film.

Although plasma may be formed by a plasma CVD method or the like when forming the first antireflection film in the film forming step, the film is formed when the plasma forming step of the modifying step is performed. Since the first gas as the raw material gas is not supplied, the film forming process and the modifying process are essentially different.

According to the method of forming an antireflection film having such a structure, first, a film forming step is carried out, for example, CVD.
The first antireflection film is formed by the method. This membrane is
Similar to the conventional antireflection film, the refractive index and the extinction coefficient have a certain correlation. Such a fixed relationship holds even when the film forming conditions are variously changed, and a specific relationship is obtained for each wavelength of the probe light for measuring the refractive index. Although the detailed mechanism by which such a relationship is established is still unknown, it is presumed that the composition of the antireflection film may be governed to some extent. However, the operation is not limited to this.

Next, a reforming process is carried out, and the second gas is supplied onto the substrate on which the first antireflection film is formed in the gas supplying step. When the plasma formation step is performed in this state, the second gas is activated, dissociated, or ionized by discharge or the like, and active species such as ions or radicals derived from the second gas are generated in the plasma and are deposited on the substrate. The first antireflective coating is exposed to these active species. Among the active species, those containing an oxygen atom oxidize the first antireflection film as an oxidation factor, and the second species in which the modified or oxidized state has progressed to the oxidized state.
The antireflection film of is obtained.

The inventor of the present invention formed a SiON film as a first antireflection film in the film formation step, and further oxidized and modified the SiON film as a second antireflection film in the modification step. As a result of measuring the refractive index and the extinction coefficient, the second refractive index and the second extinction coefficient of the second antireflection film are
It was confirmed from the certain correlation observed in the first refractive index and the first extinction coefficient of the antireflection film of No. 1. This is because at least a part of the first antireflection film is oxidized and modified by plasma treatment, and the composition of the modified portion is
It is considered that the compactness, the crystalline / amorphous state, and the like are different from those of the first antireflection film.

The plasma processing conditions (high-frequency output when high-frequency power is applied, frequency, plasma forming time, etc.) in the plasma forming step depend on the type, properties, film thickness, etc. of the first antireflection film. The second antireflection film having a desired refractive index and extinction coefficient can be easily obtained. Above all, it is assumed that adjusting the plasma formation time may change the degree of oxidation / modification of the first antireflection film, for example, the depth (film thickness) of oxidation / modification. Second anti-reflection coating
The refractive index and the second extinction coefficient of the can be sensitively and more easily controlled.

That is, in the plasma forming step, the difference between the first refractive index and the second refractive index or the first refractive index
It is preferable to adjust the plasma formation time based on the difference between the extinction coefficient and the second extinction coefficient.

In this case, for example, the refractive index with respect to the plasma formation time when the modifying process is performed on the first antireflection film whose refractive index and extinction coefficient are known under various conditions of various plasma formation times. And the variation or rate of change of the extinction coefficient is obtained in advance. Then, the first refractive index or the first extinction coefficient of the first antireflection film obtained in the actual film forming step and the second refractive index or the second extinction coefficient required of the second antireflection film. It is more preferable to set the plasma formation time according to the difference from the extinction coefficient.

Further, when high frequency power is applied to the electrodes arranged around the substrate in order to form plasma around the substrate, the frequency is not particularly limited,
It is preferably 1 to 50 MHz. Furthermore, if the output of the high frequency power is constant, the higher the frequency is, the higher the active species density is, and conversely, the active species energy tends to be smaller. When the density or energy of the active species changes in this way, it is assumed that the degree of oxidation / modification of the first antireflection film, for example, the depth (film thickness) of oxidation / modification may change. Then, it is estimated that the second refractive index and the second extinction coefficient of the obtained second antireflection film may also change.

Therefore, when the high frequency power is applied to form the plasma, the first step is performed in the plasma forming step.
It is also useful to adjust the frequency of the high-frequency power on the basis of the difference between the refractive index of 1 and the second refractive index or the difference between the first extinction coefficient and the second extinction coefficient.

In other words, in the method for forming an antireflection film according to the present invention, in other words, the first gas is supplied onto the substrate, and the refractive index and the extinction coefficient have a fixed correlation on the substrate. A film forming step of forming a first antireflection film, and a plasma around the substrate while supplying a second gas containing oxygen atoms in the molecule onto the substrate on which the first antireflection film is formed. And a modification step of modifying the first antireflection film into a second antireflection film having a refractive index and an extinction coefficient that deviate from the above-described fixed correlation. To do.

That is, in the conventional method, a combination of the refractive index and the extinction coefficient limited to a specific relationship (the above-mentioned constant correlation) could not be obtained, but the present invention provides such a specific relationship. A second antireflective coating is obtained that has an unconstrained refractive index and extinction coefficient. Therefore, conversely, it is not necessary to select the film quality of the antireflection film, particularly the optical characteristics, from the limited combination of the refractive index and the extinction coefficient, and the range of selection of such film quality can be expanded. It will be possible.

More specifically, in the film forming step, a silane-based gas as the first gas, a gas containing nitrogen atoms in the molecule, and a gas containing oxygen atoms in the molecule are supplied onto the substrate. A silicon oxynitride film (Si
An ON film) is formed, and a nitric oxide-based gas is supplied onto the substrate as a second gas in the reforming step.

Here, as the silane-based gas, unsubstituted monosilane or higher order silane, or monosilane or higher order silane in which at least one hydrogen atom in the molecule is replaced with an organic functional group or an organic non-functional group ( Organosilane gas), and the substituent is not particularly limited,
Examples thereof include an alkyl group, an alkynyl group, an alkenyl group, an alkoxyl group (alkoxy group), and a group having an aromatic ring (aryl group, aralkyl group, alkylaryl group, etc.) and the like.

When forming a film containing no oxygen atom as the first antireflection film, a silane-based gas containing no oxygen atom in the molecule is useful, and is excellent in industrial applicability and handleability. From the viewpoint, it is particularly preferable to use monosilane gas and disilane gas. On the other hand, when an oxide film is obtained as the first antireflection film, an organic silane-based gas having an oxygen-containing group such as an alkoxyl group, that is, an organic oxysilane-based gas may be used. Particularly useful organic oxysilanes include ethoxysilanes such as TEOS (tetraethylorthosilicate) and ethyltriethoxysilane. In addition, these gases can be used alone or in combination of two or more as a silane-based gas.

Examples of the gas containing nitrogen atoms in the molecule include nitric oxide gas, nitrogen (N ₂ ) gas, ammonia (NH ₃ ) gas, etc., which will be described later. Is also a nitric oxide-based gas, oxygen (O
₂ ) Gas and ozone ( ₃ ) gas.

Further, as the nitric oxide-based gas, dinitrogen oxide (N ₂ O), nitric oxide (NO), dinitrogen trioxide (N ₂ O ₃ ), nitrogen dioxide (N ₂ O), dipentapentoxide. Nitrogen (N ₂
O ₅ ), and a gas containing at least one of nitric oxide (NO ₃ ), industrial utility,
From the viewpoint of excellent stability and handleability, N ₂ O gas is preferably used. Thus, when the nitric oxide-based gas is used as the second gas, when the silane-based gas containing no oxygen atom in the molecule is used as the first gas, the first gas remaining around the substrate after the film formation process is completed. Since the reaction between the above gas and the second gas is unlikely to occur, there is an advantage that the reforming process can be carried out immediately after the film forming process.

The apparatus for forming an antireflection film according to the present invention is an apparatus for effectively carrying out the method for forming an antireflection film according to the present invention. (1) A first chamber for accommodating a substrate, A first gas supply part connected to the first chamber and supplying a first gas into the first chamber, and having a first refractive index and a first extinction on the substrate. A film forming portion in which a first antireflection film having a coefficient is formed, and (2)
A second chamber for accommodating the substrate on which the first antireflection film is formed, and a second chamber connected to the second chamber and
Has a second gas supply unit for supplying a second gas containing oxygen atoms in its molecule, an electrode installed in the second chamber, and a high-frequency power supply connected to the electrode. By applying high-frequency power output from the high-frequency power source to the electrodes, plasma is formed in the second chamber, and the first antireflection film causes the second refraction index to differ from the first refraction index. And a modified portion that is modified into a second antireflection film having a second extinction coefficient different from the first extinction coefficient.

Further, the first gas supply unit supplies a silane-based gas as the first gas, a gas containing nitrogen atoms in the molecule, and a gas containing oxygen atoms in the molecule into the first chamber. It is preferable that the second gas supply unit supplies the nitric oxide-based gas as the second gas into the second chamber.

The antireflection film according to the present invention is effectively formed by the method for forming an antireflection film according to the present invention, and has the following formula (1); k> 1.690 × n-3. 046 (1), a silicon oxynitride film (SiON) satisfying the relationship expressed by
Membrane). In the formula, k has a film thickness of 30
shows the extinction coefficient of the antireflection film in nm, and n shows the refractive index of the antireflection film in the thickness of 30 nm.
The refractive index n and the extinction coefficient k used here are n & k Analyzer 1200 and 1500 manufactured by n & k, and the probe light wavelength is 248 nm (Deep-UV ray).
Indicates the value measured when. In addition, when another measuring device is used, a method of normalizing to the measured value of the n & k Analyzer can be adopted. Examples of other measuring instruments include UV1280SE manufactured by KLA Tencor.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below. The same elements will be denoted by the same reference symbols, without redundant description. Further, the positional relationship such as up, down, left and right is based on the positional relationship shown in the drawings unless otherwise specified. The dimensional ratios in the drawings are not limited to the illustrated ratios.

FIG. 1 is a horizontal sectional view schematically showing a preferred embodiment of an antireflection film forming apparatus according to the present invention. The processing apparatus 1 has three side walls of a transfer chamber 2 having a main frame having a substantially rectangular cross section.
A twin chamber 3 in which two Si wafers W (substrates) are accommodated at the same time is combined, and a load lock chamber 6 in which load lock chambers 6a and 6b are provided is connected to the remaining side wall. Transfer chamber 2
A wafer transfer robot 23 having two extendable and retractable arm portions 21 is installed therein, and the Si wafer W is placed and held at the tip end portions of these arm portions 21. Further, each twin chamber 3 has two susceptors 5 on which the Si wafer W is placed.

FIG. 2 is a sectional view (partial configuration diagram) showing a main part of the processing apparatus 1 shown in FIG. 1, and the section of the sectional view shows a section taken along the line II-II in FIG. In the figure, the twin chamber 3 is formed by arranging two chambers 4 (also serving as a first chamber and a second chamber) side by side in a chamber housing 11. Each chamber 4 has the above-mentioned susceptor 5 on which the Si wafer W is placed, and above each susceptor 5, a shower head portion 40 having a hollow disk shape is provided.

The susceptor 5 is hermetically provided in the chamber 4 by an O-ring, a metal seal, etc., and
It is provided so as to be vertically movable by a movable mechanism (not shown). With this movable mechanism, the distance between the Si wafer W and the shower head portion 40 is adjusted. Further, the susceptor 5 is internally provided with a heater 51, which heats the Si wafer W to a desired predetermined temperature.
Furthermore, the susceptor 5 is grounded to a predetermined potential.

On the other hand, the shower head portion 40 includes a body portion 41 having a base plate as an upper wall, which is provided in common to the two chambers 4 and is provided with a gas supply port 9 for each chamber 4. Blocker plate 43 and face plate 4 in the form of a perforated plate having through holes
5 and. The body portion 41 has a concave portion that forms a substantially cylindrical internal space that communicates with the gas supply port 9, and the peripheral edge portion of the face plate 45 is coupled to the inner peripheral portion on the lower end side of the concave portion. A blocker plate 43 is installed above the face plate 45 so as to be substantially parallel to the face plate 45. The blocker plate 43 is provided between the upper wall of the body 41 and the blocker plate 43, and between the blocker plate 43 and the face plate 45. A space communicating with the gas supply port 9 is defined therebetween.

Further, a high frequency power source R grounded to the same potential as the susceptor 5 is connected to the shower head portion 40 of each chamber 4 through an impedance matching device 60 for matching impedance. The high frequency power supply R may be a fixed frequency type or a frequency variable type equipped with a frequency inverter, for example.

Furthermore, an opening 7 is provided in the lower portion of each chamber 4, and the inside of each chamber 4 is depressurized to adjust the supply flow rate of each gas from a gas supply unit 30 described later. An exhaust system 70 having a vacuum pump capable of maintaining the pressure inside each chamber 4 at a constant pressure is connected via a valve system V.

The valve system includes, for example, a two-blade type turbo throttle valve arranged on the upstream side (twin chamber 3 side) and an isolation valve arranged on the downstream side (exhaust system 70 side). It can be configured, and a gate valve may be added. The type of vacuum pump used for the exhaust system 70 is not particularly limited, and examples thereof include a turbo molecular pump with a dry pump and the like.

In the twin chamber 3, a monosilane (SiH ₄ ) gas supply source 31 (first gas supply section) and a dinitrogen oxide (N ₂ O) gas supply source 32 (first gas supply section and first gas supply section The gas supply unit 30 having a helium (He) gas supply source 33 and a nitrogen (N ₂ ) gas supply source 34 is also connected. These gas supply sources 31 to 34 are MFCs that control the supply flow rate of each gas.
(Mass flow controller) 31a, 32a, 33a, 3
It is connected to the gas supply port 9 of each shower head portion 40 via a pipe 10 provided with 4a.

As a result, S as a raw material gas for film formation is obtained.
iH ₄ gas and N ₂ O gas, the N ₂ O gas as a gas reforming, He gas as a carrier gas or diluent gas, as well as the N ₂ gas as a purge gas as required, a shower head of each chamber 4 The blocker plate 43 and the face plate 45 are introduced into the section 40.
Is supplied to each chamber 4 via. In this way, the film forming unit is constituted by each chamber 4 and the gas supply unit 30. Further, the reforming unit is configured by the chambers 4, the gas supply unit 30, the high frequency power sources R, and the impedance matching units 60.

The pipe 10 is connected to a cleaning system 8 which employs remote plasma processing. The cleaning system 8 includes a reactor cavity 81 arranged on the pipe 10 side and an MFC 8
It has a supply source 82 of a gas containing fluorine atoms, such as NF ₃ gas, connected through 2a. The reactor cavity 81 is equipped with a microwave generator (not shown) for generating plasma,
The NF ₃ gas as the cleaning gas supplied from the gas supply source 82 is dissociated to generate active species, and mainly neutral active species are supplied into the chamber 4 depending on the conditions.

Although not shown, the inner space of the chamber 4 on the front surface side and the inner space of the chamber 4 on the back surface side of the Si wafer W are gas-sealed from each other. That is, from the gas supply unit 30 to the shower head unit 4 on the front surface side.
Each gas is supplied through 0, and the back side is supplied with a purge gas from a back side purge system (not shown) so that both gases do not flow into the space regions on the opposite side.

An example of the method for forming an antireflection film according to the present invention using the processing apparatus 1 thus constructed will be described. Each operation described below of the processing apparatus 1 is controlled by a control device (system) (not shown) or manually based on an automatic operation or an operation by an operator. FIG. 3 is a flowchart showing the flow of processing including the procedure of one embodiment of the method for forming an antireflection film according to the present invention. In addition, FIGS. 4A to 4D
FIG. 4A is a process diagram showing a state in which an antireflection film is formed on the Si wafer W by the procedure shown in FIG.

First, prior to the formation of the antireflection film, Si
A base layer 101 made of Al, polysilicon, or the like is formed on the base layer 100 of the wafer W (step S1; FIG. 4A).
reference). Next, the exhaust system 70 is operated to reduce the pressure in each chamber 4 to a predetermined pressure. Under this reduced pressure, the wafer transfer robot 23 moves the load lock chambers 6a, 6a and 6b.
The Si wafer W having the underlayer 101 previously held in b is transferred into the predetermined twin chamber 3 via the transfer chamber 2.

Next, the two Si wafers W are placed and housed on the susceptors 5 in the two chambers 4 provided in the twin chamber 3. After that, He gas is supplied from the gas supply source 33 through the pipe 10 into both chambers 4, and the pressure is adjusted so that the inside of each chamber 4 has a constant pressure. After the pressure in each chamber 4 is stabilized, SiH ₄ gas, N ₂ O gas, and He gas are supplied from the respective gas supply sources 31 to 33 to the respective shower head parts 40 through the pipe 10. At this time, the pressure in each chamber 4 is preferably 250 to 1600 Pa (2
~ 12 Torr), more preferably 500-1300P
It is adjusted to be a (4 to 10 Torr).

The supply flow rate of each gas at this time varies depending on the properties of the antireflection film to be finally formed, the volume of the chamber 4, etc., and can be set appropriately, but the thickness is about 100 to 400 Å. When forming the ultra-thin film, the flow rate range shown below is suitable, for example.・ SiH ₄ gas: 50 to 200 ml / min (sccm) ・ N ₂ O gas: 100 to 600 ml / min (sccm) ・ He gas: 2000 to 8000 ml / min (sccm) Further, SiH ₄ gas supply flow rate and N ₂ It is suitable to supply both gases so that the ratio to the supply flow rate of O gas is preferably 1: 1 to 1: 4, more preferably 1: 2 to 1: 3. By appropriately adjusting the supply flow rate ratio of the both gases, the refractive index and the extinction coefficient of the antireflection film 102 can be set to any combination of values that satisfy a certain correlation.

Each gas introduced into the inner space of each shower head portion 40 from the gas supply port 9 in this manner is dispersed and sufficiently mixed by the blocker plate 43, and the blocker plate 43 and the face are passed through the plurality of through holes. It flows out into the space between the plate 45. The mixed gas flows out below the shower head portion 40 through the plurality of through holes of the face plate 45, and is supplied onto the Si wafer W placed on the susceptor 5.

On the other hand, while supplying these gases into each chamber 4, electric power is supplied to the heater 51 of the susceptor 5 to heat the Si wafer W to a predetermined temperature via the susceptor 5. In this case, the temperature of the Si wafer W (substrate temperature, film formation temperature) is preferably 100 ° C. or higher, more preferably 350 to 500 ° C. As a result, the film forming raw material gas reaching the Si wafer W is reacted.

Immediately above the Si wafer W, various elementary reactions (thermochemical reactions) occur and are involved in a complicated manner, and the active species (controlling factor) of the chemical species depending on the equilibrium and rate-limiting conditions according to the state of the reaction field. ) Is generated, various intermediate products are formed by the reaction of these chemical species, and the antireflection film 102 (first antireflection film) made of a SiON film is deposited and formed on the Si wafer W (step S2). , Film forming step; see FIG. 4B). The thickness of the antireflection film 102 is preferably not too thick, for example, several nm to 300 nm, and further several nm, from the viewpoint that the effect of modification described later is sufficiently exhibited.
The present invention can be extremely effective for the antireflection film 102 having a film thickness of ˜100 nm.

After the film forming process is carried out for a time corresponding to the film forming speed until the antireflection film 102 having a predetermined film thickness is formed,
Stop the supply of each gas. Then, continuously or as necessary, the gas remaining in each chamber 4 is purged with He gas or N ₂ gas, and then N ₂ O gas is supplied from the gas supply source 32 to each showerhead unit 40 through the pipe 10. Yes (gas supply step). At this time, each chamber 4
The internal pressure is preferably 250-1600 Pa (2-1
2 Torr), more preferably 400-1300 Pa
Adjust to be (3 to 10 Torr).

After the pressure in the chamber 4 becomes stable, the high frequency power is output from the high frequency power supply R and the shower head section 40 is operated.
Apply to. As a result, the Si wafer W in the chamber 4 is
Plasma is formed in the upper space by glow discharge (plasma formation step). At this time, the impedance matcher 60 causes the combined impedance of the impedance of the plasma and the impedance of the impedance matcher 60 to be on the plasma (strictly, glow discharge part) side of the high frequency power supply R, that is, the output of the high frequency power supply R. Match the impedance. Here, the condition of the high frequency power is not particularly limited, but examples thereof include the following conditions.・ Frequency: 1 to 50 MHz ・ Output: 0.2 to 5 kW

If this frequency is less than 1 MHz, it tends to be difficult to obtain a sufficient active species density in plasma. On the other hand, if the frequency exceeds 50 MHz, it tends to be difficult to obtain sufficient active species energy. The output is 0.
When it is less than 2 kW, there is a tendency that the plasma processing efficiency cannot be sufficiently enhanced. On the other hand, if this output exceeds 5 kW, arcing discharge may occur in the chamber 4.

Active species such as ions and radicals derived from N ₂ O gas are generated in the plasma, and the antireflection film 102 on the Si wafer W is exposed to these active species. Active species containing oxygen atoms (eg, O ^* , NO ^*, etc.) are
As an oxidation factor, the antireflection film 102 is oxidized from the surface layer portion or diffused to oxidize the inside or the interface portion. The portion of the antireflection film 102 that is in contact with the oxidation factor is further oxidized to change its composition, and the antireflection film 103 in which at least a part of the film is modified is formed (step S3, modification process;
(See FIG. 4C).

At least a part of the antireflection film 103 thus obtained by the oxidation / reformation is the antireflection film 10
2, the composition, the denseness of the film, and the like may be significantly different. As a result, the refractive index (first refractive index) and the extinction coefficient (first extinction coefficient) satisfying a certain correlation expressed by the antireflection film 102 are significantly different from each other (second refractive index). ) And an extinction coefficient (second extinction coefficient).

Here, the plasma processing conditions (including the above-mentioned high-frequency power condition) in the plasma forming step can be appropriately set according to the type, properties, film thickness, etc. of the antireflection film 102. Further, by changing the plasma processing conditions appropriately, it is possible to develop a desired refractive index and extinction coefficient in the antireflection film 103. In particular, by adjusting (adjusting) the plasma formation time, that is, the process time when the Si wafer W is plasma-processed in the plasma formation step, and / or the frequency of the high frequency power, the oxidation / reformation of the antireflection film 102 is performed. The degree of
For example, it is assumed that the depth (film thickness) of oxidation / modification changes, and the refractive index and extinction coefficient of the antireflection film 103 can be controlled sharply and easily.

In this case, as an example, the plasma processing conditions in which the plasma formation time and / or the frequency of the high frequency power output from the high frequency power supply R are variously changed with respect to the antireflection film 102 whose refractive index and extinction coefficient are known. In step S3
The modification step is carried out in the same manner as above, and the variation or change rate of the refractive index and the extinction coefficient with respect to the plasma formation time and / or the frequency of the high frequency power is obtained in advance. Then, the refractive index or extinction coefficient of the antireflection film 102 obtained in the actual film forming step (step S3), and the refractive index or extinction coefficient required (that is, the target) of the antireflection film 103. There is a method of setting the required plasma formation time and / or the frequency of the high frequency power from the relationship of the variation or the rate of change of the refractive index and the extinction coefficient obtained previously according to the difference of

After a lapse of a predetermined time, the high frequency power source R
Then, the application of the high frequency power to the shower head unit 40 is stopped, and step S3 as the reforming process is ended. Next, the Si wafer W on which the antireflection film 103 is formed is carried out from each chamber 4, and the organic photosensitive resin composition for photoresist is applied onto the antireflection film 103 of the Si wafer W by, for example, spin coating. The resist film 104 is applied to form a resist film 104 (step S4; see FIG. 4D). afterwards,
Exposure is performed using a mask, and further development is performed to perform processing such as transferring the mask pattern onto the Si wafer W.

According to the processing apparatus 1 thus constructed and the method for forming an antireflection film using the processing apparatus 1, step S2 is performed.
In each chamber 4, Si having an underlayer 101
After the antireflection film 102 made of the SiON film is formed on the wafer W, step S3 is continuously performed in the same chamber 4, the antireflection film 102 is subjected to N ₂ O plasma treatment, and at least a part thereof is oxidized.・ Reform. The antireflection film 103 thus obtained is considered to be different from the antireflection film 102 in the composition, density, crystalline / amorphous state, etc. of the modified portion thereof. A refractive index n and an extinction coefficient k that are significantly different from those of the antireflection film 102 are developed.

The combination of the refractive index and the extinction coefficient exhibited by the antireflection film 102 shows a certain constant correlation as in the conventional case even if the film forming conditions in step S2 are variously changed, whereas the antireflection film is formed. The element 103 can realize any combination of the refractive index n and the extinction coefficient k that are not bound to the correlation (in other words, deviate from the correlation). Therefore, for example, it is possible to obtain the antireflection film 103 capable of exhibiting the desired refractive index n and extinction coefficient k required by lithography depending on the underlying layer 101.

In step S3, the plasma processing conditions in the plasma forming step are appropriately set according to the type, property, film thickness, etc. of the antireflection film 102.
The refractive index n and the extinction coefficient k of the antireflection film 103 can be easily controlled. Among these plasma processing conditions, plasma formation time and / or high frequency power source R
By adjusting the frequency of the high-frequency power output from the antireflection film 102, the degree of oxidation / reformation of the antireflection film 102, for example, the depth (film thickness) of oxidation / reformation can be changed significantly and reliably. The refractive index n and the extinction coefficient k of the antireflection film 103 can be controlled sharply and more easily.

Further, since N ₂ O gas, which has lower reactivity with the silane-based gas than O ₂ gas or O ₃ gas, is used as the reforming gas, SiH ₄ gas is used as the film-forming raw material gas as described above. In the embodiment, after performing the film forming process in step S2, the plasma treatment in step S3 can be performed without discharging the residual SiH ₄ gas in the chamber 4. Therefore, the processing efficiency and thus the throughput can be improved.

The present invention is not limited to the above-described embodiment, and for example, step S2 (film forming step)
In, in the same manner as in step S3 (reforming step) described above, plasma may be formed by applying high frequency power.
The condition of the high frequency power in this case is not particularly limited, and examples thereof include the following conditions.・ Frequency: 1 to 50 MHz ・ Output: 0.01 to 1 kW

Further, the apparatus for forming the antireflection film is not limited to the apparatus having the twin chamber 3 like the processing apparatus 1, and may be a CVD chamber composed of a monochamber or a system provided in the CVD chamber main frame. Furthermore, as the reforming gas, N ₂ O is used.
O ₂ gas or the like may be used in place of the gas. In this case, after the antireflection film 102 is formed in step S2, the chamber 4 is once purged to leave SiH ₄ remaining in the chamber 4. There is an advantage that the reaction between the gas and O ₂ gas can be suppressed. In addition, the first gas as the film forming raw material gas and the second gas as the reforming gas are not limited to those in the above embodiment.

[0060]

EXAMPLES Hereinafter, specific examples according to the present invention will be described, but the present invention is not limited thereto.

<Embodiment 1> The processing apparatus 1 shown in FIGS.
A processing device (Applied Materials, Inc .; a device based on Producer (registered trademark)) having the same configuration as the above was prepared. Using this apparatus, the antireflection film 102 (film thickness: approximately 30 nm) was formed on the Si wafer W (step S
2). At this time, the pressure inside each chamber 4 of the twin chamber 3 was reduced to about 9.5 Torr, and SiH ₄ gas, N ₂ O gas, and He gas were supplied at 100 sccm and 240 sccm, respectively.
And after supplying for 10 seconds at a flow rate of 4400 sccm,
High frequency power of 13.56 MHz is applied to the shower head 40 at an output of 70 W to form plasma for 10 seconds.
A film was formed.

Then, SiH ₄ gas, N ₂ O gas and He
The gas supply was stopped, the valve system V was opened for 5 seconds to exhaust the residual gas in the chamber 4, and then N ₂ O gas was supplied into the chamber 4 at a flow rate of 4000 sccm to a pressure of about 2.5 Torr. After that, high frequency power of 13.56 MHz was applied to the shower head portion 40 at an output of 240 W to form plasma, and plasma treatment was performed for 30 seconds.
Next, the application of high frequency power is stopped and N ₂ is applied for 10 seconds.
After continuing the supply of O gas, high frequency power of 13.56 MHz was applied again to the shower head portion 40 at an output of 240 W to form plasma, and the plasma treatment was performed again for 30 seconds. As a result, the antireflection film 102 was oxidized and modified to form the antireflection film 103.

Table 1 shows the main processing conditions. In the table,
The chambers A and B indicate the two chambers 4 provided in the twin chamber 3, and the gas flow rate under the film forming conditions and the reforming conditions is the total supply flow rate to both chambers A and B. The other conditions are common to both chambers. Further, “RF” in the table indicates high frequency power, and “spacing” indicates a distance (distance) between the lower surface of the face plate 45 of the shower head unit 40 and the upper surface of the Si wafer W.

Example 2 An antireflection film 103 was formed in the same manner as in Example 1 except that the SiH ₄ gas flow rate during film formation was 115 sccm. The main processing conditions are shown in Table 1.

<Comparative Examples 1 to 13> Without carrying out the reforming step,
The antireflection film 102 (film thickness: is formed on the Si wafer W using the same apparatus as that used in Examples 1 and 2 except that the film forming conditions in the film forming step are changed as shown in Table 1.
(Approximately 30 nm) was deposited.

<Measurement of Refractive Index n and Extinction Coefficient k> For the antireflection films formed in Examples 1 and 2 and Comparative Examples 1 to 13, n & k Analyzer 120 manufactured by n & k was used.
0 and 1500, the probe light wavelength is 248 nm
(Deep-UV ray), refractive index n and extinction coefficient k
Was measured. Table 1 also shows the measurement results of the refractive index n and the extinction coefficient k.

[0067]

[Table 1]

FIG. 5 is a graph showing measurement data of the refractive index n and the extinction coefficient k obtained for the antireflection films formed in Examples 1 and 2 and Comparative Examples 1 to 13.
In FIG. 5, the white symbols indicate the data of the antireflection film of the example, and the black symbols indicate the data of the antireflection film of the comparative example.

As shown in FIG. 5, the antireflection film of the comparative example obtained by the conventional film-forming method in which the reforming step is not performed has various conditions such as the flow rate of the raw material gas for film-forming. It was confirmed that the refractive index n and the extinction coefficient k show a substantially constant correlation. As a result of fitting the data of Comparative Examples 1 to 13 by linear least squares approximation, the following expression (2); k = 1.690 × n−3.046 (2) (Indicated by a straight line Lk) was obtained. Here, in the formula, k represents an extinction coefficient, and n represents a refractive index.

On the other hand, the SiO 2 obtained in Examples 1 and 2
The refractive index n and the extinction coefficient k of the antireflection film 103 made of the N film are out of this correlation, and are expressed by the following formula (1); k> 1.690 × n−3.046 (1) It was confirmed that a refractive index n and an extinction coefficient k satisfying the relationships shown were developed.

[0071]

As described above, according to the method and apparatus for forming an antireflection film according to the present invention, the first antireflection film obtained by performing the film forming step is subjected to the plasma treatment to obtain the first antireflection film. Since the second antireflection film formed by oxidizing and modifying the above antireflection film is formed, it is possible to realize an antireflection film exhibiting an arbitrary and desired refractive index and extinction coefficient that could not be achieved conventionally. Therefore, the antireflection film formed by the method and apparatus for forming an antireflection film of the present invention exhibits desired refractive index and extinction coefficient.

[Brief description of drawings]

FIG. 1 is a horizontal sectional view schematically showing a preferred embodiment of an apparatus for forming an antireflection film according to the present invention.

FIG. 2 is a sectional view (partial configuration diagram) showing a main part of the processing apparatus 1 shown in FIG.

FIG. 3 is a flowchart showing a processing flow including a procedure of an embodiment according to a method for forming an antireflection film according to the present invention.

4A to 4D are process diagrams showing a state in which an antireflection film is formed on the Si wafer W by the procedure shown in FIG.

5 is a refractive index n and an extinction coefficient k obtained for the antireflection films formed in Examples 1 and 2 and Comparative Examples 1 to 13. FIG.
It is a graph which shows the measurement data of.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Processing apparatus (antireflection film forming apparatus), 4 ... Chamber (1st chamber, 2nd chamber), 5 ... Susceptor,
8 ... Cleaning system, 30 ... Gas supply part, 31 ... Gas supply source (first gas supply part), 32 ... Gas supply source (second gas supply part), 40 ... Shower head part, 51 ... Heater, 60 ... impedance matcher, 70 ... exhaust system, 10
1 ... Underlayer, 102 ... Antireflection film (first antireflection film), 103 ... Antireflection film (second antireflection film), 10
4 ... Resist film, R ... High frequency power source, W ... Si wafer (base).

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tsutomu Shimayama             14-3 Shinsen, Narita-shi, Chiba Nogedaira Industrial Park               Applied Materials Japan             Within the corporation F-term (reference) 2H025 AA02 AA03 DA34                 2K009 AA05 BB04 CC01 CC02 CC14                       CC42 DD03 DD08 DD09 DD12                       DD17                 4K030 AA01 AA06 BA29 BA35 CA04                       CA12 DA08 LA11                 5F046 PA03 PA04 PA12

Claims (7)

[Claims] 1. A film forming step of supplying a first gas onto a substrate to form a first antireflection film having a first refractive index and a first extinction coefficient on the substrate, A gas supply step of supplying a second gas containing oxygen atoms to the substrate on which the first antireflection film is formed, and forming plasma around the substrate on which the first antireflection film is formed. And a second extinction coefficient different from the first extinction coefficient of the first antireflection film, and a second extinction coefficient different from the first extinction coefficient. A method of forming an antireflection film, which comprises: a reforming step of modifying the second antireflection film having: 2. In the plasma forming step,
A difference between the first refractive index and the second refractive index, or
2. The method for forming an antireflection film according to claim 1, wherein the plasma formation time is adjusted based on the difference between the first extinction coefficient and the second extinction coefficient. 3. A first gas is supplied onto a substrate, and the refractive index and the extinction coefficient have a constant correlation on the substrate.
And a second gas containing oxygen atoms in the molecule is supplied to the substrate on which the first antireflection film is formed while plasma is formed around the substrate. And forming a second antireflection film having a refractive index and an extinction coefficient that deviate from the predetermined correlation.
And a modification step of modifying the antireflection film into the antireflection film. 4. In the film forming step, a silane-based gas as the first gas, a gas containing a nitrogen atom in the molecule,
And supplying a gas containing oxygen atoms in the molecule onto the substrate to form a silicon oxynitride film as the first antireflection film, and in the modifying step, a nitric oxide-based film as the second gas. The method for forming an antireflection film according to claim 1, wherein a gas is supplied onto the substrate. 5. A first chamber containing a substrate, and a first gas supply unit connected to the first chamber and supplying a first gas into the first chamber. Therefore, a film forming portion in which a first antireflection film having a first refractive index and a first extinction coefficient is formed on the substrate, and a substrate in which the first antireflection film is formed are A second chamber that is housed therein; and a second chamber that is connected to the second chamber and that contains an oxygen atom in the molecule in the second chamber.
A second gas supply unit for supplying the gas, a high frequency power supply connected to the electrode and an electrode installed in the second chamber, and a high frequency power output from the high frequency power supply. Is applied to the electrode, plasma is formed in the second chamber, and the first antireflection film has a second refractive index different from the first refractive index and the first antireflection film.
Forming a second antireflection film having a second extinction coefficient different from the extinction coefficient. 6. The silane-based gas as the first gas, the gas containing a nitrogen atom in the molecule,
And supplying a gas containing oxygen atoms in the molecule into the first chamber, wherein the second gas supply unit uses a nitric oxide-based gas as the second gas in the second chamber. The apparatus for forming an antireflection film according to claim 5, wherein the apparatus is for supplying the antireflection film. 7. An antireflection film is formed by the method according to claim 1, and is represented by the following formula (1); k> 1.690 × n−3.046 (1) ), K: extinction coefficient at a film thickness of 30 nm, n: refractive index at a film thickness of 30 nm, comprising a silicon oxynitride film.