JP3395348B2 - Method of forming antireflection film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor integrated circuit, and more particularly to a method for forming an antireflection film used in the lithography process.

[0002]

[Prior art and its problems] With the increase in device density, wiring technology is becoming more and more miniaturized and multilayered. However, high integration may be a factor that reduces the reliability of the device.

This is because the step of the interlayer insulating film becomes large and steep due to the miniaturization of wiring and the progress of multi-layering, and the processing accuracy and reliability of the wiring formed thereon are lowered. Therefore, in order to improve the resolution while extending the life using the current lithography technology, first, it is necessary to improve the flatness of the interlayer insulating film. This is becoming important from the viewpoint of a decrease in the depth of focus due to the shortening of the wavelength of lithography.

[0004]

Another important problem is how to suppress the reflection from the base and maintain the resolution of the resist. Therefore, a technique of forming a so-called antireflection film under the resist is becoming mainstream. One of the candidates for this antireflection film is the SiON film proposed by the present applicant (Japanese Patent Application No. 4-
359750). However, since the antireflection film itself is very thin, the film formation time is very short in the conventional plasma CVD (plasma CVD that can form a film at a low temperature is preferable because it may be formed on the Al film). However, there was a problem in reproducibility of film thickness and film quality.

Particularly, for the antireflection film composed of the SiON film, the reproducibility of the film quality is a key point because the optical constants such as n and k are controlled by the contents of N and O. Therefore, there was an urgent need to solve the problem.
Further, since the film thickness of the antireflection film also greatly affects the antireflection effect during photolithography, it is necessary to control the film thickness of the antireflection film with high precision.

The present invention has been made in view of the above circumstances.
An object of the present invention is to improve reproducibility such as film quality and film thickness when an antireflection film is formed on a lower layer of a resist or the like to form a fine pattern.

[0007]

The inventors of the present invention have earnestly studied a method for forming an antireflection film capable of improving reproducibility such as film quality and film thickness. Since the film time was as short as about 10 seconds, the initial state in which the plasma was unstable occupies a large proportion of the film formation time, and it was considered that the reproducibility was deteriorated. Therefore, the present inventor thinks that if the plasma is unstable, an unstable state may be used, and if it is stable, only the stable state may be selectively used, and by using any one of these states,
By forming an antireflection film, it was found that the reproducibility of conditions such as film quality and film thickness was improved, and the present invention was completed.

Namely, when the method of forming the antireflection film according to the present invention, an antireflection film, intermittent plasma C
The VD method is used for the processing steps of the intermittent plasma CVD method.
It is characterized by using a shutter for limiting film formation . The antireflection film is preferably a compound containing at least silicon, nitrogen and oxygen.

In the processing step of the intermittent plasma CVD method, the antireflection film is repeatedly formed at a timing of a predetermined time immediately after the plasma is formed . Predetermined time timing for film formation is preferably 1 to 5 seconds. The intermittent time (no film formation is performed) between the film formation process and the next film formation process is preferably 1 to 5 seconds.
Furthermore, the number of repetitions of film formation is preferably 2 to 12 times,
More preferably, it is 3 to 6 times.

[0010]

Function: The stability of the plasma is somewhat poor for a few seconds immediately after the plasma is formed. However, since the poor stability itself is reproducible, the film thickness and the film thickness can be reduced by using this as a counter only during the initial time when plasma is formed, that is, when the intermittent plasma is repeated for several seconds. The reproducibility of the film quality is improved.

Further, in the processing step of the intermittent plasma CVD method, a shutter for limiting film formation is used ,
By forming a predetermined time using a sheet Yatta, it improves the reproducibility of the film thickness and film quality. As the film forming apparatus of this with shutter, the shutter with film forming device to which the present applicant has already filed (Japanese Patent Laid-Open No. 5-243185)
Can be used.

[0012]

EXAMPLES Specific examples of the present invention will be described below. Here, prior to the description of the actual film forming process, first, a magnetic field microwave plasma CVD apparatus used for carrying out the present invention will be described with reference to FIG.

FIG. 1 is a schematic view of a magnetic field microwave plasma CVD apparatus used for carrying out the present invention. The apparatus will be briefly described. The microwave 2 generated by the McNetron 1 is transferred to a reaction chamber 5 surrounded by a quartz bell jar 4 through a waveguide 3 and installed so as to surround the reaction chamber 5. The solenoid coil 6 generates a microwave frequency (2.45 GHz) and a magnetic field (8.75 × 10 ^-2 T) that causes so-called ECR discharge, thereby generating a gas plasma 7.

A substrate 8 such as a semiconductor wafer on which an antireflection film is formed is transported by a transporting unit (not shown) so as to be placed on the susceptor 9 and placed on the susceptor 9. The susceptor 9 is heated by using the heater 10, which also heats the substrate 8. The gas is introduced through the gas introduction pipe 11, and is exhausted from the exhaust pipe 12 by an exhaust system (not shown).

Further, inside the quartz bell jar 4, a shutter 13 for appropriately restricting the flow of the plasma 7 on the surface of the substrate 8 is mounted. That is, the shutter 13 is
The quartz bell jar 4 is mounted to be openable and closable so as to limit film formation (film deposition) on the surface of the substrate 8. In addition,
The opening / closing mechanism of the shutter 13 is not particularly limited as long as it can be opened and closed, and various means such as a slide movement mechanism, a rotation movement mechanism, or a shutter movement mechanism used for a camera can be adopted. Also, shutter 1
No. 3, the structure is not particularly limited as long as plasma ions can be appropriately shielded, and a metal mesh or the like can be used.

Example 1 Hereinafter, an example of actually forming an antireflection film by using the method for forming an antireflection film according to the present invention will be described with reference to FIGS. In this example, intermittent plasma CVD was performed using the magnetic field microwave plasma CVD apparatus shown in FIG. 1 to form an antireflection film. In addition,
A description of a portion not related to the essence of the present invention is omitted, and FIG. 2 shows a device simplified as compared with an actual device.

As shown in FIG. 2A, a polycide film 102 having a film thickness of 200 nm, for example, was formed on a substrate 101 by an ordinary low pressure CVD method. Polycide film 10
For No. 2, a silicide film such as a tungsten silicide film is formed on the polysilicon film.

Next, as shown in FIG. 2B, an antireflection film 103 was formed on the polycide film 102 under the conditions shown in Table 1 below using the apparatus shown in FIG. The antireflection film 103 is not particularly limited, but in this embodiment, it is SiON: H (nitrogen oxide silicon containing hydrogen).

[0019]

[Table 1] Gas flow rate: SiH ₄ / N ₂ O = 20/40 SCCM Pressure: 1.33 Pa Microwave: 850 W (2.45 GHz) RF bias: 0 W Film formation time: 3 seconds × 4 times intermittent time: 3 seconds × Three times at this time, as shown in FIG. 3, the opening / closing control of the shutter 13 shown in FIG. 1 is performed so that only the film forming condition a is selected.
By repeating this (four times in the example), a film having good reproducibility could be formed. The film forming condition a is a condition for a few seconds from immediately after the plasma is formed, and is a state before the plasma is stabilized, but the state is reproducible. The term “immediately after the plasma is formed” may be substantially immediately after the plasma is formed, and the term “immediately after” according to the present invention for a few seconds after the plasma is formed.

Reference Example 1 A reference example of the present invention will be shown with reference to FIGS. Here again, the description of the parts not related to the essence of the present invention is omitted, and FIG. 2 shows a device simplified as compared with the actual device.

As shown in FIG. 2A, a polycide film 102 having a film thickness of 200 nm, for example, was formed on a substrate 101 by a normal low pressure CVD method. Polycide film 10
For No. 2, a silicide film such as a tungsten silicide film is formed on the polysilicon film.

Next, as shown in FIG. 2B, an antireflection film 103 was formed on the polycide film 102 under the conditions shown in Table 1 below using the apparatus shown in FIG. The antireflection film 103 is not particularly limited, but in this embodiment, it is SiON: H (nitrogen oxide silicon containing hydrogen).

[0023]

[Table 2] Gas flow rate: SiH ₄ / N ₂ O = 20/40 SCCM Pressure: 1.33 Pa Microwave: 850 w (2.45 GHz) RFbias: 0 W Film formation time: 3 seconds × 4 times Intermittent time: 3 seconds × 3 At this time, as shown in FIG. 3, opening / closing control of the shutter 13 shown in FIG. 1 is performed so that only the film forming condition b is selected.
By repeating this (four times in the example), a film having good reproducibility could be formed. The film forming condition b is a condition of several seconds after about 10 seconds has passed immediately after the plasma is formed, and the plasma is stable.

The present invention is not limited to the above-mentioned embodiments, and the configuration, conditions, etc. can be changed as appropriate without departing from the scope of the present invention. For example, the plasma CVD apparatus used in the method of the present invention is not limited to a magnetic field microwave plasma CVD apparatus, but an ICP (Inductive coupled plasma) CVD apparatus,
Helicon wave plasma CVD equipment, TCP (Transformer
A coupled plasma) CVD apparatus, a parallel plate electrode type CVD apparatus, or another plasma CVD method may be used. The antireflection film is not limited to SiON: H (nitrogen oxide silicon containing hydrogen), but may be amorphous SiC: H.
(Hydrogen-containing silicon carbide) or amorphous C: H (hydrogen-containing carbon) may be used.

Further, the lower layer film on which the antireflection film is formed is not limited to the polycide film, but may be a polysilicon film, an aluminum alloy film, an aluminum film, a tungsten film,
The silicide film or an insulating film such as an interlayer insulating film is not particularly limited.

[0026]

As described above, according to the method for forming an antireflection film of the present invention, it is possible to obtain an antireflection film having good reproducibility such as film thickness and film quality, which is a bottleneck in the prior art. The semiconductor integrated circuit can be manufactured by a reliable process.

[Brief description of drawings]

FIG. 1 is a schematic view of a magnetic field microwave plasma CVD apparatus used for carrying out the present invention.

2A and 2B are schematic cross-sectional views showing a process of forming an antireflection film.

FIG. 3 is a time chart diagram showing an intermittent timing of a method of forming an antireflection film according to an embodiment of the present invention.

[Explanation of symbols]

1; magnetron 101; substrate 2; microwave 102; polycide film 3; waveguide 103; antireflection film 4; quartz bell jar 5; reaction chamber 6; solenoid coil 7; gas plasma 8; substrate 9; susceptor 10; heater 11 Gas inlet pipe 12; exhaust pipe 13; shutter

Continuation of the front page (56) Reference JP-A-6-85075 (JP, A) JP-A-1-252782 (JP, A) JP-A-5-243185 (JP, A) JP-A-4-361531 (JP , A) JP 58-46635 (JP, A) JP 62-28765 (JP, A) JP 62-216329 (JP, A) JP 1-243413 (JP, A) JP 4-85823 (JP, A) JP 5-218010 (JP, A) JP 5-335244 (JP, A) JP 7-235393 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) H01L 21/027 G03F 7/11 503 C23C 16/50 H01L 21/205 H01L 21/3065

Claims (2)

(57) [Claims] 1. A method of forming an antireflection film, wherein the antireflection film is formed by using an intermittent plasma CVD method, and a shutter for limiting the film formation is used in the processing step of the intermittent plasma CVD method , In the above intermittent plasma CVD, the plasma generated directly
Repeatedly after a predetermined time, repeat the above anti-reflection
A method for forming an antireflection film, which comprises forming a stop film . 2. The method for forming an antireflection film according to claim 1, wherein the antireflection film is a compound containing at least silicon, nitrogen and oxygen.