KR100223328B1 - Fabrication method of anti-reflection coating film for decreasing reflection of exposing light of high reflective substrate - Google Patents

Abstract

The present invention relates to a method for manufacturing a reflective stopper film for reducing the reflection of exposure light of a high reflectivity substrate, wherein the composition of the reflective stopper film is matched to the RI of the initial deposition substrate, and at the end of the deposition, the reflection is prevented according to the RI value of the PR to be coated thereon. Minimize the reflection of exposure light to PR when using a conventional single-layer reflection blocking film by synthesizing a reflection blocking film with a gradient RI value that can be several hundreds of micrometers regardless of the thickness of the film. Since the optimum RI value of the ARC and the thin film thickness are interlocked with each other, when the optimum ARC thickness is several thousand micrometers, the step difference due to the reflection blocking film itself and the unisotropic etching of the reflection blocking film become serious. Solve the problem.

Description

Manufacturing method of reflective low-thin film for reducing the reflection of exposure light of high reflectivity substrate

1 is a cross-sectional view showing a plurality of ARC layers formed on a lower substrate according to the method of the present invention

2 is a schematic diagram of PECVD equipment

* Explanation of symbols for main parts of the drawings

1 to 3: Reflective stopper film 4: Photosensitive film

21 chamber 22,23 up and down electrode

24,25: Generator 26: Heater Block

27 gas injector 28 semiconductor substrate

29: MFC (Mass Flow Controller) 30: Control Bus

The present invention relates to a method for manufacturing a reflective stopper film for reducing the reflection of exposure light of a high reflectivity substrate, and particularly, a gradient RI (Gradient Refractive Index) value that can minimize the reflection of exposure light with a minimum thickness even on a high reflection substrate. The present invention relates to a method for manufacturing a reflective stopper film that facilitates a subsequent planarization process and an anti-reflective coating (ARC) etching process by forming a reflective blocking film having a minimum step increase.

In the semiconductor device manufacturing process, the antireflection thin film controls exposure light between a DUV photoresist (PR) and a high reflectance substrate in a deep ultra-violet (DUV) exposure process. It is inserted for the purpose of adjusting the composition and physical properties of the ARC thin film according to the deposition time.

In other words, the antireflection film optimizes the optical characteristics, thereby minimizing the re-reflection of exposure light to the PR to prevent short circuits or short circuits formed.

As the manufacturing technology of the antireflection film, other applications include surface coating of solar cell condensing window, or chemical vapor deposition method for smoothly connecting the joints of two materials having greatly different lattice constants during hetero-crystal growth. Can be used.

In order to minimize the re-reflection of exposure light to PR due to high reflectivity substrate in DUV (248nm) or higher short wavelength exposure process, it is placed between PR and substrate of ARC thin film of single composition. And the optical properties of the underlying substrate.

The optical constant RI value and thickness of ARC for vertical incident light are determined to minimize R reflected by PR on the surface of ARC expressed by Equation (1) below.

To minimize the second term on the right side of equation (1) below In order to minimize the first term, the thickness of cos δ is 0, that is, δ = π / 2.

R ∝ n ² _ARC (n _PR -n _s ) ² cos ² δ + (n _PR n _s -n ² _ARC ) ² sin ² δ--Equation (1)

(Where n _PR : real RI of PR, n _s : real RI of substrate, n _ARC : RI of ARC )

Therefore, in order for the ARC layer to act as an existing single layer, it is necessary to select the composition of ARC in consideration of the RI value of each substrate, and then calculate its thickness. It can be set up to thousands of degrees.

If the ARC thickness is selected to be 1000 Å or more, there are problems such as an increase in the level difference and isotropic etching during dry etching for pattern formation. Therefore, it is preferable to reduce the thickness of the ARC to 300 Å or less.

Accordingly, the present invention is a method of forming a reflection blocking film in the concept of a multilayer film instead of the conventional single layer in view of the above problems, the gradient RI value that can minimize the reflection of the exposure light to a minimum thickness even on a high reflectivity substrate It is an object of the present invention to provide a method for manufacturing a reflective blocking film.

The method of the present invention for achieving the above object,

In the method of manufacturing a multilayer anti-reflection film is inserted between the photosensitive film and the high reflectance substrate during the exposure process of the semiconductor device to reduce the re-reflection of exposure light to the photosensitive film,

The RI value of the antireflection film positioned on the uppermost layer of the multilayer antireflection film in contact with the photoresist film is similar to the RI value of the photoresist film, and the RI value of the lowest antireflection film in contact with the high reflectivity substrate is formed similarly to the RI value of the substrate. ,

It is characterized in that the RI value of the reflection blocking film is formed to change linearly in the thickness direction of the reflection blocking film.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a cross-sectional view showing a plurality (x) of ARC layers formed on a lower substrate according to the method of the present invention.

Referring to FIG. 1, within several hundred microseconds of ARC, there are x several tens of multi-layered films (1 to 3) having optical constants linearly varying in thickness. Reflectivity by the three layers of the layer 3, the PR layer 4, and the x-1 layer 2 is calculated as shown in Equation (2) below.

In other words, in the formula (1), n _ARC → n _x , n _s → n _x−1 is replaced with each other. The RI values are similar to (n _PR- n _x-1 ) on the right side of Equation (2) below. Since the two terms are close to zero, the reflection to PR by the multi-layer ARC is minimized regardless of the δ related to the thickness.

In the manufacturing method described above, the ARC material should vary widely from the optical property PR to the optical property of the substrate according to the deposition conditions. Also, as the deposition method, PE CVD (Plasma Enhanced CVD), CVD, or physical vapor deposition (Physical) Vapor Deposition) is possible.

The present invention is a method of manufacturing a multilayer ARC film in which the RI value (n-ik, n: real value of RI, k: imaginary value of RI) changes linearly according to the ARC thickness. It is mentioned that silicon oxynitride is used as the ARC material, and the deposition is performed by PECVD. Synthesis gas of silicon oxynitride can be mixed with an inert gas such as Ar instead of SiH ₄ + N ₂ O + N ₂ or N ₂ . It may take several to ten seconds.

The main parameters of the PECVD equipment for changing the RI values are the composition ratio of the mixed gas, the plasma generation power, the substrate temperature, the reaction chamber pressure, and the like, and the optical constant value in the thickness direction is changed by changing these factors within the time that the thin film is synthesized. Adjust

2 is a schematic diagram of a PECVD equipment.

Referring to FIG. 2, unlike conventional PECVD equipment, mass flow controllers (MFCs) 29, pressure controllers, and RF generators 24 and 25 for respective gases are different. For example, a temperature controller must be able to time-control the PC.

For example, the RI value at 248 nm of the ARC silicon oxynitride thin film deposited by PECVD using a mixed gas of SiH ₄ + N ₂ O + N ₂ is increased as the SiH ₄ / N ₂ O ratio increases. The value is increased.

Therefore, to synthesize an ARC thin film having a gradient RI value at a constant thickness, the flow rate of SiH ₄ gas is fixed, and the flow rate of N ₂ O MFC is controlled to increase linearly during the deposition time from 0 to several hundred sccm. At the beginning of deposition, the RI value of the high-reflectivity substrate, for example, WSi has an RI value similar to 1.96-I2.69, and at the end of the deposition it is similar to the RI value of PR (n-ik = 1.8-i0.011). To have a value.

In addition, the RI value of the silicon nitride thin film also changes in the RF power generation that generates the plasma. The RI value is high when the power is low and the RI value is low when the thin film is synthesized at high power. ARC having a gradient RI value can be synthesized.

At this point, other variables can achieve the same result.

Another embodiment of the present invention is to be used as a reflection blocking film of the light incident from the solar cell to absorb the light as much as possible, the solar cell generally using a doped amorphous silicon (amorphous Silicon) In addition, the lower layer portion adjusts the PECVD process parameters over time to have a RI value similar to that of amorphous silicon, so that the optical constant value has a linear gradient RI value in a direction perpendicular to the thin film surface.

As described above, when the conventional ARC using only a single layer is used, the optimum RI value and the thin film thickness of the ARC for minimizing the reflection of exposure light to the PR are interlocked with each other. In case of, the step increase by ARC itself and the problem of unisotropic etching of ARC are serious. However, in the present invention, the composition of ARC is adjusted to RI of the initial deposition substrate, and at the end of deposition, the ARC is adjusted according to the RI value of the PR to be coated on top. The above-mentioned problems can be solved by synthesizing ARC having a gradient RI value, which can be several hundreds of millimeters thick regardless of the composition.

Claims (9)

In the method of manufacturing a multilayer antireflection film inserted between the photosensitive film and the high reflectivity engine during the exposure process of a semiconductor device to reduce the re-reflection of exposure light as a photosensitive film, The RI value of the antireflection film positioned on the uppermost layer of the multilayer antireflection film in contact with the photoresist film is similar to the RI value of the photoresist film, and the RI value of the lowest antireflection film in contact with the high reflectivity substrate is formed similarly to the RI value of the substrate. , And the RI value of the reflective stopper film is changed in a linear direction along the thickness direction of the reflective stopper film to reduce the reflection of exposure light of a high reflectivity substrate. The method of claim 1 The light used in the exposure process is a method for manufacturing a reflective stopper film for reducing the reflection of exposure light of a high reflectivity substrate, characterized in that the short wavelength of less than 248nm. The method of claim 1 The material of the anti-reflection film is a silicon oxynitride, characterized in that the anti-reflective film manufacturing method for reducing the reflection of the exposure light of the high reflectivity substrate. The method of claim 1 The method of manufacturing a reflective stopper film for reducing the reflection of exposure light of a high reflectivity substrate, characterized in that the deposition method using a PECVD method or a CVD method to change the RI value of the reflection stopper film. The method of claim 4 In the deposition method, the anti-reflective thin film manufacturing for reducing the reflection of exposure light of the high reflectivity substrate, characterized in that by adjusting the composition ratio of the mixed gas to adjust the mass flow for each gas in order to change the RI value Way. The method of claim 4 In the PECVD method, an alternating current generator (24,25), which is a plasma generation source, is adjusted to 0 to 1000 W according to the deposition time to adjust the RI value. Way The method of claim 6 In the alternator, when the frequency is 13.56 MHz, when the frequency is 0 to 1 MHz, and when the frequency is 2.45 MHz, the modulation is changed according to time to change the RI value. Reflective stopper film for manufacturing method. The method of claim 4 In the deposition method, in order to adjust the substrate temperature and the pressure of the reaction chamber according to the deposition time, the temperature controllers are used at room temperature to 500 ° C., and the pressure controller is 0.001 to 10 Torr. Method of manufacturing a low-reflection thin film for reducing reflection. The method of claim 1 The thickness of the reflective stopper film is set to several hundreds of microns or less, and the optical constant value in the vertical direction of the thin film is linearly, quadratic, or polynomial. Method of manufacturing a low-reflection thin film for reducing reflection.