KR100253589B1 - Method of forming fine pattern of semiconductor device - Google Patents

Abstract

PURPOSE: A method for forming a fine pattern of a semiconductor device is provided to improve the characteristic and reliability of a semiconductor device by etching a lower layer using a photoresist film pattern. CONSTITUTION: A transparent thin film is formed on a semiconductor substrate(40) having a high reflective rate. A dual anti-reflective layer is formed by sequentially forming an amorphous silicon layer and a silicon oxynitride layer on the transparent thin film. Then, a photoresist film pattern is formed on the dual anti-reflective layer. The dual anti-reflective layer and the transparent thin film are etched by using the photoresist film pattern as a mask. Then, the photoresist film pattern is removed. The dual anti-reflective layer includes a polycrystalline silicon/silicon oxynitride layer.

Description

Micro pattern formation method of semiconductor device

The present invention relates to a method of forming a fine pattern of a semiconductor device, in particular, during the exposure process for device isolation and contact process, the pattern of the mask is transferred to the substrate constantly regardless of the thickness of the diffuse reflection layer present on the high reflectivity substrate, The present invention relates to a technique for forming an antireflection film that minimizes pattern nonuniformity and distortion due to notching or swinging phenomenon due to diffuse reflection.

1 (a), 1 (b) and 2 are cross-sectional views and graphs showing a method for forming a fine pattern of a semiconductor device according to the prior art, and are related to device isolation and contact processes.

Referring to FIG. 1A, a photosensitive film 13 is coated on a semiconductor substrate 10 in a laminated structure of an oxynitride film 12 / silicon oxide film layer 11 / semiconductor substrate 10.

The device isolation region is formed by exposing the semiconductor substrate 10 by an exposure and development process using the device isolation mask (not shown).

In the device isolation region, a thermal oxide film is formed by oxygen diffusion. At this time, the silicon nitride film 12 is to secure the maximum device formation region by suppressing the oxide film growing in the lateral direction during the thermal oxide film forming process by oxygen diffusion.

In this case, as the wavelength of the light source is shortened during the exposure process, the reflectance of the semiconductor substrate is increased, the die size is increased, and the pattern size is reduced to 0.3 μm or less, so that the size of the photosensitive film pattern d1 'and d2' for device isolation is increased. Is not constant. (d1 ′ ≠ d2 ′)

The reason is that the photoresist pattern is proportional or inversely proportional to the intensity of the exposure light distributed in the photoresist film. Since the light source reflected by the high reflectance engine is completely transmitted without being absorbed by the intermediate silicon oxide film / nitride film, the fine pattern of the silicon oxide film / nitride film This is because the rereflection rate to the photosensitive film is greatly changed by the step. Therefore, when the device is manufactured in this manner, the characteristics of each unit device may be different.

Referring to FIGS. 1B and 2, first, an isolation layer 21, a gate oxide 22, and a word line 23 are formed on the semiconductor substrate 20, and the top of the semiconductor substrate 20 is planarized. The silicon oxide film 24 is formed.

Then, a photoresist pattern (not shown) is formed on the silicon oxide layer 24 by an exposure and development process using a contact mask (not shown).

In this case, the exposure process is performed using a light source of 365nm and 248nm.

In addition, since the silicon oxide film 24 existing between the photoresist pattern, the semiconductor substrate 20 and the word line 23 is completely reflected without absorbing the exposure light of the light source, there is a slight difference in thickness of the silicon oxide film 24. This significantly changes the re-reflection rate to the photosensitive film.

Next, contact holes 25 and 26 exposing the semiconductor substrate 20 and the word line 23 are formed using the photoresist pattern as a mask.

Referring to FIG. 2, the optical properties of the silicon oxide film at the wavelengths of 365 nm and 248 nm vary greatly periodically with the photoresist depending on the thickness of the oxide film.

In this case, the change in re-reflection means a change in the size of the contact hole, and in a severe case, the contact hole may not be formed.

As described above, in the prior art, when there is a material without light absorption at an exposure wavelength of 365 nm or 248 nm, such as a transparent insulating film, for example, a silicon oxide film or a silicon nitride film, between the high reflectance substrate and the photosensitive film, the transparent insulating film is a substrate. If there is a thickness difference of about 200 ~ 700Å within, due to the reinforcement canceling interference caused by this thickness difference, the re-reflectance of the exposure light to the photosensitive film is different by 0.1 ~ 05, and therefore, the same size should be formed in each part of the substrate. The pattern varies greatly depending on the location. As a result, there is a problem in that it is impossible to form a pattern having a predetermined size, thereby lowering the yield and characteristics of the semiconductor device and consequently making it difficult to integrate the semiconductor device.

The present invention is to solve the above problems of the prior art, by forming a double-layered anti-reflection film on the layer having a high step height and high power factor and by using the patterning process to perform a fine pattern bonded to the high integration of semiconductor devices It is an object of the present invention to provide a method for forming a fine pattern of a semiconductor device, which can be formed to improve the characteristics and yield of the semiconductor device and thereby enable high integration of the semiconductor device.

1 (a) and 1 (b) are cross-sectional views showing a method for forming a fine pattern of a semiconductor device according to the prior art.

FIG. 2 is a graph showing reflectivity according to FIG. 1 (b). FIG.

3 (a) to 3 (f) are cross-sectional views showing a method for forming a fine pattern of a semiconductor device according to an embodiment of the present invention.

* Explanation of symbols for main parts of the drawings

10,20,40: semiconductor substrate 11,41: pad oxide film

12,42: pad nitride film 13: photosensitive film

21: device isolation insulating film 22: gate oxide film

23 word line 24 silicon oxide film

25, 26: contact hole 43: amorphous silicon

44 silicon oxynitride film 46 oxygen or N ₂ O plasma

47: photosensitive film pattern

In order to achieve the above object, the method for forming a micropattern of a semiconductor device according to the present invention comprises the steps of forming a transparent thin film such as an oxide film, a nitride film, and the like on the semiconductor substrate having a high step difference and a high reflectance, and amorphous silicon on the transparent thin film. Forming a layer and a silicon oxynitride film sequentially to form a double antireflection film, forming a photoresist pattern on the double antireflection film, and etching the double antireflection film and the transparent thin film using the photoresist pattern as a mask. It is a 1st characteristic that it includes the process and the process of removing the said photosensitive film pattern.

In addition, the method for forming a micropattern of a semiconductor device according to the present invention includes the steps of forming a first pad insulating film and a second pad insulating film on a semiconductor substrate having a step difference, and an amorphous silicon layer and a silicon acid on the second pad insulating film. Forming a nitride film sequentially to form a double anti-reflection film; plasma processing the double anti-reflection film; forming a photoresist pattern on the double anti-reflection film; and performing double reflection using the photoresist pattern as a mask. Etching the protection film and the second pad insulating film; removing the photoresist pattern; and etching the first pad insulation film and the remaining double anti-reflection film to expose a predetermined portion of the semiconductor substrate. A second feature includes a step of forming a film.

In addition, the method of forming a fine pattern of a semiconductor device according to the present invention comprises the steps of forming a device isolation insulating film and a gate electrode on the semiconductor substrate, forming an insulating film to planarize the surface of the semiconductor substrate, and amorphous on the insulating film Forming a silicon layer and a silicon oxynitride film sequentially to form a double antireflection film, plasma processing the double antireflection film, forming a photoresist pattern on the double antireflection film, and masking the photoresist pattern And a process of forming a contact hole exposing a predetermined portion of the semiconductor substrate and the gate electrode, removing the photoresist pattern, and removing the double anti-reflection film.

On the other hand, the principle of the present invention for achieving the above object, the light source of the exposure process is not incident to the transparent insulating film, such as the oxide film, nitride film or oxynitride film in order to form a uniform device isolation pattern and uniform contact pattern formation. By inserting an anti-reflective film, which is a thin light absorber in the middle, the conventional technique inserts a general single layer anti-reflective film between the transparent insulating film and the photosensitive film, and the anti-reflective film absorbs about 50% of the exposure light, but the rest is transparent. Since the light incident on the film and reflected at the junction of the transparent film-high reflectivity substrate is emitted to the photosensitive film, the anti-reflective film acts as a reflection inhibiting agent for a specific thickness of the transparent insulating film, but at other thicknesses, the photosensitive film cannot be prevented because the light is not blocked. Uneven pattern formation However, the present invention forms a double anti-reflection film structure having a function of absorbing exposure light almost like an amorphous silicon and removing exposure light transmitted through the transparent film such as amorphous silicon, thereby forming a photoresist / double antireflection film / transparent In the device isolation pattern exposure step and the contact pattern exposure step having the laminated structure of the insulating film / high reflectivity substrate, the pattern size is not influenced by the thickness difference of the transparent insulating film so that a uniform pattern can be obtained.

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

3 (a) to 3 (f) are cross-sectional views illustrating a method of forming a fine pattern of a semiconductor device according to an embodiment of the present invention, and related to a technology of forming an element isolation insulating film in a portion having a step.

First, the pad oxide film 41 and the pad nitride film 42 are formed in the region where the semiconductor substrate 40 is to be separated.

In addition, a thin layer of amorphous silicon 43 that absorbs exposure light is deposited on the pad nitride layer 42.

In this case, the amorphous silicon 43 is a material having a large imaginary refractive index (k) at an exposure wavelength, such as polycrystalline silicon, and may be used by replacing a material having a large imaginary refractive index such as polycrystalline silicon. Here, the amorphous silicon 43 or polycrystalline silicon has an imaginary refractive index value of about 3.65 and 3.5 at 248 nm, respectively, and may vary slightly depending on the degree of crystallization.

The light absorption coefficient "α" of amorphous and polycrystalline silicon is

α = 4πk / λ... … … … … … … … … … First Formula

(Where α is the light absorption coefficient, k is the imaginary refractive index, and λ is the exposure wavelength)

It determined by the first equation, and, at the exposure wavelength of the optical absorption coefficient of the amorphous and polycrystalline silicon of 248nm can be seen in each of the determined 0.0185Å ^-1, 0177Å ^-1.

In addition, since the thickness of 248 nm decreases to 37% (= e ⁻¹ ) as the light and the 248 nm progress into the amorphous and polycrystalline silicon, respectively, the thickness of the exposure light may be absorbed at a small thickness of about 200 μs.

However, in terms of surface roughness of the thin film, the amorphous silicon 43 is more smooth than the polycrystalline silicon, which is advantageous as a light absorption film.

Meanwhile, the amorphous silicon 43 may be deposited using a furnace type chemical vapor deposition (CVD) or plasma-enhanced CVD (hereinafter referred to as PECVD). Proceed to In addition, the deposition thickness is about 100 to 500 kPa in which exposure light does not pass through the pad nitride film 42. In the deposition conditions, SiH ₄ or Si ₂ H ₆ is used as the silicon source, and in some cases, the hydrogen gas is diluted to reduce the thickness uniformity and deposition rate, and the high frequency power is 0 to 1000 W. Is 0.01 ~ 10 Torr, the substrate temperature is synthesized in the range of room temperature ~ 700 ℃ degree. (Fig. 3 (a))

Next, a silicon oxynitride film 44 is formed on the amorphous silicon 43 to form an antireflection film in a stacked structure of the amorphous silicon 43 and the silicon oxynitride film 44.

At this time, the silicon oxynitride film 44 is formed to a thickness of about 100 ~ 500Å by PECVD method.

Here, the silicon oxynitride film 44 has a refractive index having a real part of 1.5 to 2.5 and an imaginary part of 0.1 to 1.5 at 248 nm. In addition, when the silicon oxynitride film 44 is amorphous silicon 43 at the bottom and deep-UV photoresist at the top, the optimum real refractive index, the imaginary refractive index, and the thickness are 2.1 ± 0.2, 0.5 ± 0.2, and 300, respectively. ± 50 Hz.

The silicon oxynitride layer 44 is formed by PECVD, but SiH ₄ 0-300 sccm, N ₂ O 0-500 sccm, NH ₃ 0-300 sccm, N ₂ 0-5000 sccm, He 0-5000 sccm A flow rate of degree is used, in particular the NH ₃ gas may not be mixed in some cases.

The silicon oxynitride film 44 is formed at a reaction chamber pressure of 0.01 to 10 Torr, a substrate temperature of 100 to 500 ° C, and a high frequency power of 0 to 1000W. At this time, N ₂ and He gas may be mixed in a large amount as a diluent gas for the purpose of reducing the film uniformity and deposition rate. (Fig. 3 (b))

Next, in order to improve photoresist patterning after deposition of the silicon oxynitride film 44, the surface treatment is performed using an oxygen plasma or an N ₂ O plasma 46.

In this case, the plasma treatment process may obtain a uniform device isolation photoresist pattern even when the thickness of the pad oxide film 41 and the pad nitride film 42 is uneven. (Fig. 3 (c))

Next, a photoresist pattern 47 is formed on the silicon oxynitride layer 44. In this case, the photoresist pattern 47 is formed by an exposure and development process using an element isolation mask (not shown).

Here, the photoresist pattern 47 is formed of the same distance between the device isolation regions, that is, a predetermined size of d1 and d2 (d1 = d2). (Fig. 3 (d))

Next, the silicon oxynitride layer 44, the amorphous silicon 43, and the pad nitride layer 42 are sequentially etched using the photoresist pattern 47 as a mask.

In this case, the etching process may be performed under an etching condition of an etching selectivity of the silicon oxynitride layer 44, the amorphous silicon 43, and the pad nitride layer 42 of 1 to 3: 1, and the silicon oxynitride layer 44. And the amorphous silicon 43 is etched. The pad nitride layer 42 is etched using the photoresist pattern 47 as a mask. (Fig. 3 (e))

Then, the photosensitive film pattern 47 is removed. In addition, the silicon oxynitride layer 44 and the amorphous silicon 43 may be completely removed under an etching condition in which the etching selectivity of the pad nitride layer 42, the amorphous silicon 43, and the pad oxide layer 41 is 1 to 3: 1. At the same time, a pad nitride film 42 pattern and a pad oxide film 41 pattern are formed to expose a predetermined portion of the semiconductor substrate 40. (Fig. 3 (f))

Another embodiment of the present invention is to form contact holes in two portions having a step, the principle of which is to form a pattern of a predetermined size using a thin film of a dual structure as in the embodiment of the present invention.

As described above, in the method of forming a micropattern of a semiconductor device according to the present invention, a layered structure of amorphous silicon and a silicon oxynitride film is formed between the photosensitive film and the transparent thin film, and a uniform pattern is formed by performing a patterning process of the photosensitive film. There is an advantage that the yield of the semiconductor device can be greatly improved by making the characteristics of the device uniform within and improving the reliability of the bonding of the interlayer wiring.

Claims (26)

Forming a transparent thin film such as an oxide film or a nitride film on the high-difference, high reflectivity semiconductor substrate, forming a double anti-reflection film by sequentially forming an amorphous silicon layer and a silicon oxynitride film on the transparent thin film; Forming a photoresist pattern on the double antireflection film, etching the double antireflection film and the transparent thin film using the photoresist pattern as a mask, and removing the photoresist pattern; Way. The method of claim 1, wherein the double antireflection film is formed in a stacked structure of a polysilicon / silicon oxynitride film. Forming a first pad insulating film and a second pad insulating film on the semiconductor substrate having a step difference, forming a double anti-reflection film by sequentially forming an amorphous silicon layer and a silicon oxynitride film on the second pad insulating film; Plasma-processing the double anti-reflection film, forming a photoresist pattern on the double anti-reflection film, etching the double anti-reflection film and the second pad insulating film using the photoresist pattern as a mask, and the photoresist pattern And forming a first and second pad insulating layer pattern to expose a predetermined portion of the semiconductor substrate by etching the first pad insulating layer and the remaining double anti-reflective layer. The method of claim 3, wherein the first pad insulating layer is an oxide film. The method of claim 3, wherein the second pad insulating layer is a nitride film. The method of claim 3, wherein the amorphous silicon is formed to a thickness of 100 to 500 kV by PECVD. The method of claim 3, wherein the amorphous silicon is formed to a thickness of 100 to 500 kV using a thermal CVD method. The method of claim 7, wherein the amorphous silicon is formed using SiH ₄ or Si ₂ H ₆ gas at a flow rate of 10 to 10,000 sccm. The method of claim 7, wherein the amorphous silicon is formed by diluting H ₂ gas in a flow rate of 10 to 30,000 sccm in SiH ₄ or Si ₂ H ₆ gas. The method of claim 9, wherein the amorphous silicon is formed by diluting a N ₂ gas at a flow rate of 10 to 30,000 sccm instead of H ₂ gas. 4. The method of claim 3, wherein the amorphous silicon is formed using a plasma generation frequency of 13.56 MHz and power of 0 to 10000 W at a pressure of 0.01 to 10 Torr, a substrate temperature of 600 to 600 ° C. Way. The method of claim 3, wherein the amorphous silicon is formed at a substrate temperature of 400 ° C. to 900 ° C. at a pressure of 0.01˜760 Torr. The method of claim 3, wherein the silicon oxynitride layer has a real refractive index and an imaginary refractive index at 248 nm in a range of 2.1 ± 0.1 and 0.5 ± 0.2, respectively. The method of claim 3, wherein the silicon oxynitride layer is formed to a thickness of 300 ± 50 μs. The method of claim 3, wherein the silicon oxynitride film is formed by a PECVD method. The method of claim 3, wherein the silicon oxynitride film is SiH ₄ or Si ₂ H ₆ gas 0 ~ 500 sccm, N ₂ O gas 0 ~ 1000 sccm, NH ₃ gas 0 ~ 300 sccm, N ₂ gas 0 ~ 5000 sccm, H ₂ Method for forming a fine pattern of a semiconductor device, characterized in that the gas is formed using a flow rate of 0 ~ 5000 sccm. The method of claim 3 or 16, wherein the silicon oxynitride film is formed by mixing N ₂ and H ₂ diluent gases. The method of claim 3, wherein the silicon oxynitride film is formed under a pressure of 0.01 to 10 Torr, a substrate temperature of 100 to 500 ° C., and a high frequency (13.56 MHz) power of 0 to 1000 W. 5. The method of claim 3, wherein the double anti-reflection film is formed in a polycrystalline silicon / silicon oxynitride layer stacked structure. The method of claim 3, wherein the double anti-reflection film is formed in an in-situ process without vacuum braking. The method of claim 3, wherein the plasma processing step is performed using an oxygen plasma or an N ₂ O plasma film. The fine pattern of the semiconductor device of claim 3, wherein the etching process of the double anti-reflection film and the second pad insulating film is performed by using an etching selectivity ratio of the double anti-reflection film and the second pad insulating film to be 1: 1 to 3. Formation method. The semiconductor device of claim 3, wherein the etching process of the double anti-reflection film and the first pad insulating film is performed by using an etching selectivity of the double anti-reflection film and the first pad insulating film as 1 to 3: 1. Formation method. Forming a device isolation insulating film and a gate electrode on the semiconductor substrate, forming an insulating film to planarize the surface of the semiconductor substrate, and forming an amorphous silicon layer and a silicon oxynitride film on the insulating film sequentially to form a double anti-reflection film. Forming a film, performing a plasma treatment on the double antireflection film, forming a photoresist pattern on the double antireflection film, and exposing a predetermined portion of the semiconductor substrate and the gate electrode using the photoresist pattern as a mask. And forming a hole, removing the photoresist pattern, and removing the double antireflection film. 25. The method of claim 24, wherein the double antireflection film is formed in a stacked structure of polysilicon and a silicon oxynitride film. 25. The method of claim 24, wherein the plasma processing step is performed using oxygen plasma or N ₂ O plasma.

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