JP2586383B2 - Method of forming reflection and interference prevention resin 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 forming a reflection and interference preventing resin film in a lithography process for manufacturing a semiconductor device.

[0002]

2. Description of the Related Art An antireflection film using a resin can reduce reflected light from the semiconductor substrate side due to interference of light generated in the film. In addition, the anti-interference film using resin,
The multiple interference effect generated in the photosensitive resin film (resist) due to the interference of light generated in the film can be reduced. This process is, for example, a top anti-reflector process.

[0003] These processes have been receiving attention in recent years for the following reasons.

(1): Exposure light changes from i-ray (365 nm) to excimer laser light (248 nm), the influence of interference in the photosensitive resin film increases, and the pattern size changes with respect to the change in the thickness of the photosensitive resin film. The change has become so large that it cannot be ignored.

[0005] (2): With the miniaturization of patterns, deformation of pattern shapes due to reflection cannot be ignored.

However, the anti-reflection film and the anti-interference film both need to be shifted in phase by 180 degrees in each film, so that strict film thickness control is required. Taking the anti-interference film as an example, the film thickness must be as in the following equation (1).

[0007]

For example, in i-line lithography,
λ = 365 nm: N = 1.47 (for PVA): n =
If it is set to 1, d = 62 nm, and the film thickness of the interference prevention film must be controlled so that the film thickness changes within 5% at 62 nm. That is, if the film thickness deviates more than 5% from the condition that the phase becomes 180 degrees, the effect cannot be obtained.

At present, anti-reflection and anti-interference resin films are:
The film is formed by the same spin coating method as the photosensitive resin film.

FIG. 6 is a schematic view showing a conventional method, in which an anti-reflection and anti-interference resin is applied from a nozzle 4 above a central portion of a semiconductor wafer (semiconductor substrate) 1 mounted on a spin chuck 2. The material liquid for the film is dropped, and the material liquid is applied by rotating the semiconductor wafer together with the spin chuck.

[0011]

However, the anti-reflection and anti-interference resin film formed by applying the above method has a film thickness variation range of 25 over the entire surface of the semiconductor wafer as shown in the film thickness distribution diagram of FIG. %, And the film thickness uniformity of 5% or less cannot be satisfied.

On the other hand, in coating for forming a photosensitive resin film, various attempts have been made to make the film thickness as uniform as possible. However, since the photosensitive resin film and the anti-reflection and anti-interference resin film targeted by the present invention have completely different film thicknesses, their viscosities and the required degree of uniformity, a coating technique for forming the photosensitive resin film is used. Is not applicable. That is, the standard thickness of the photosensitive resin film is 700 to
Although it is 2000 nm, the standard thickness of the anti-reflection and anti-interference resin film is 60 to 100 nm. Also, the viscosity of the photosensitive resin film material applied by spin coating and the viscosity of the anti-reflection and anti-interference resin film material are extremely different, and the precision and uniformity of the film formation required for the anti-reflection and anti-interference resin film are extremely high. Stricter. That is, as described above, in the anti-reflection and anti-interference resin film, it is necessary to delay the phase of the exposure light passing through the film by 180 degrees, so that the film thickness variation in the wafer surface must be kept within 5%.

[0013]

A feature of the present invention is that, in a lithography process for manufacturing a semiconductor device, a film is formed between a semiconductor substrate and a photosensitive resin film or on a photosensitive resin film so as to reflect exposure light and reduce exposure light. in the method for forming a reflection and anti-interference resin film to prevent interference upon applying the material liquid by dropping a material solution for forming the film from a nozzle onto a semiconductor wafer by rotating the semiconductor wafer, the semiconductor
One nozzle is arranged above the center of the body wafer,
Multiple nozzles located above the periphery of the semiconductor wafer
And the semiconductor wafer is received from one nozzle above the central portion.
The concentration or viscosity of the material liquid dropped at the center of Eha
From a plurality of respective nozzles above the peripheral portion
The concentration of the material liquid dropped on the periphery of the semiconductor wafer
Alternatively, there is a method for forming a reflection and interference prevention resin film having a high viscosity .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings.

FIG. 1 is a view showing a coating method in a method of forming a reflection and interference prevention resin film according to an embodiment of the present invention. A semiconductor wafer 1 having a diameter of 6 inches is mounted on a spin chuck 2 and a central portion thereof. Nozzle 3 above 3a '
a, and four peripheral portions 3b ', 3c', 3d ',
Nozzles 3b, 3c, 3d, 3 above each of 3e '
e (nozzles 3d and 3e are not shown). In addition, the nozzles 3b, 3 from the central part
c, 3d, 3e are each separated by 3.5 cm.

When PVA (polyvinyl alcohol) is used for the reflection and interference prevention resin film, a 1.5% P
A VA solution (a solution in which water was used as a solvent and 1.5 wt% of PVA was used as a solute) was used as a material solution A, and a concentration of 2.0 was used.
% PVA solution (water is used as a solvent and 2.0 wt% P
A solution in which VA is mixed as a solute) is prepared as a material liquid B. The viscosity of the material liquid A is about 1 cp and the material liquid B
Are greater than this.

The material liquid A is dropped from the nozzle 3a onto the central portion 3a 'of the semiconductor wafer, and the material liquid B having a higher concentration and viscosity than the material liquid A is supplied from the nozzles 3b, 3c, 3d and 3e to the peripheral portion 3b of the semiconductor wafer. ', 3c', 3d ', 3
Drop each on e ′. After dropping, the semiconductor wafer is
Rotate at 0 rpm for 10 seconds and continue 2,000
Spin at 20 rpm for 20 seconds to complete the application.

By baking the coated semiconductor wafer on a hot plate at 100 ° C. for 60 seconds, the variation in film thickness from the center to the periphery of the semiconductor wafer is within 5% as shown in FIG. A reflection and interference prevention resin film having good film thickness uniformity was obtained.

In FIG. 3, the concentration of the material liquid from the nozzle 3a dropped to the center is fixed at 1.5%, and the concentration of the material liquid from the nozzles 3b, 3c, 3d, 3e dropped to the periphery is changed. 6 is a graph showing a variation in film thickness in the case. The other conditions are the same as in the above embodiment. When the peripheral portion has the same concentration of 1.5% as the central portion, the film thickness variation is 2 as in the prior art of FIG.
5%. When the density at the peripheral portion is 1.75%, the variation in film thickness is reduced to about 10%. When the density at the peripheral portion is 2.0% in the embodiment, the variation in film thickness is minimized.
There is a concentration range where the film thickness variation is 5% or less centering on 0%. Conversely, when the concentration was further increased to 2.25%, the film thickness variation became 10%.

FIG. 4 is a sectional view showing an example in which the present invention is used for forming an interference prevention film in the order of steps. The aluminum film 12 is patterned by a photolithography process on a semiconductor wafer 1 having an aluminum film 12 deposited on the entire surface of a semiconductor substrate 11 on which a predetermined impurity region is formed and a necessary lower layer wiring structure is formed, thereby forming aluminum wiring. If so, the aluminum film 12
A photosensitive resin film (resist) 6 is formed thereon by spin coating, and PVD is formed thereon by the method of the present invention described with reference to FIG.
A solution 7 '(material solution A and material solution B) is applied (A) and baked to obtain PVA with good film thickness uniformity
A film 7 is formed (B). Next, the exposure light 8 is applied to the selected area of the photosensitive resin film 6 through the PVA film 7 (C).
At this time, the PVA film functions as the interference prevention resin film 7.
Then, the resist mask 1 is removed from the photosensitive resin film 6 by development.
6 is formed, and the PVA film 7 is removed during this development (D). Thereafter, the aluminum film 12 is etched using the resist mask 16 as a mask to pattern and form an aluminum wiring.

FIG. 5 is a sectional view showing an example in which the present invention is used for forming an antireflection film in the order of steps. The aluminum film 12 is patterned by a photolithography process on a semiconductor wafer 1 having an aluminum film 12 deposited on the entire surface of a semiconductor substrate 11 on which a predetermined impurity region is formed and a necessary lower layer wiring structure is formed, thereby forming aluminum wiring. If so, the aluminum film 12
In the method of the present invention described above with reference to FIG.
(Material liquid A and material liquid B) are applied (A) and baked to form a PVA film 7 with good film thickness uniformity (B). Next, a photosensitive resin film (resist) is formed on the PVA film 7.
6 is formed by spin coating, and the selected area of the photosensitive resin film 6 is irradiated with exposure light 8 (C).
The film functions as an anti-reflection resin film 7. Then, a resist mask 16 is formed from the photosensitive resin film 6 by development,
Exposed portions of the PVA film 7 other than under the resist mask 16 are removed during this development (D). Thereafter, the aluminum film 12 is etched using the resist mask 16 as a mask to pattern and form an aluminum wiring.

[0022]

As described above, according to the present invention, a material liquid for a reflection and interference prevention resin film having different concentrations or viscosities is dropped and applied to a central portion and a peripheral portion of a semiconductor wafer. A reflection and interference prevention resin film having a film thickness variation of 5% or less can be formed.

[Brief description of the drawings]

FIGS. 1A and 1B are diagrams illustrating an embodiment of the present invention, wherein FIG. 1A is a cross-sectional view and FIG. 1B is a plan view of a semiconductor wafer.

FIG. 2 is a diagram showing a variation in the thickness of a reflection and interference prevention resin film obtained by a method according to an example of the present invention.

FIG. 3 is a diagram showing a change in the thickness variation of the reflection and interference prevention resin film when the concentration of the material liquid dropped on the central portion of the semiconductor wafer is constant and the concentration of the material liquid dropped on the peripheral portion is changed. It is.

FIG. 4 is a cross-sectional view showing an example in which a PVA film according to an embodiment of the present invention is used as an interference prevention resin film.

FIG. 5 is a sectional view showing an example in which a PVA film according to an embodiment of the present invention is used as an anti-reflection resin film.

FIG. 6 is a diagram illustrating a conventional technique.

FIG. 7 is a diagram showing a variation in thickness of a reflection and interference prevention resin film according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Semiconductor wafer 2 Spin chuck 3, 4 Dropping nozzle 6 Photosensitive resin film (resist) 7 PVA film 7 'PVA solution 8 Exposure light 11 Semiconductor substrate 12 Aluminum film 16 Resist mask

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code Agency reference number FI Technical display location H01L 21/30 564D

Claims (1)

(57) [Claims] In a lithography process for manufacturing a semiconductor device, a reflection and interference prevention resin film formed between a semiconductor substrate and a photosensitive resin film or on a photosensitive resin film to prevent reflection and interference of exposure light. In the method of forming, a material liquid constituting the film is dropped from a nozzle onto a semiconductor wafer, and when the material liquid is applied by rotating the semiconductor wafer, one nozzle is provided above a central portion of the semiconductor wafer. Arrangement
And a plurality of nozzles above a peripheral portion of the semiconductor wafer.
From one nozzle above the center and the half
The concentration or the concentration of the material liquid dropped onto the center of the conductive wafer
Is the number of each of the nozzles above the periphery
The material liquid dropped onto the periphery of the semiconductor wafer from the wafer
A method of forming a reflection and anti-interference resin film, characterized by having a high concentration or viscosity .