JP2003332310A - Method for forming organic film pattern and method for manufacturing solid-state image pickup device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To remove a resist mask together with its hardened superficial film, without damaging the organic base film after the organic film patterning, in the formation of an organic film pattern. <P>SOLUTION: The method for forming an organic film pattern comprises a step of forming an organic film 12 on a substrate 11; a step of patterning the organic film 12 via a resist mask 13 by dry etching using a plasma gas comprising oxygen as the main component; a step of ashing a hardened layer 15 on the resist mask 13, by using a plasma gas which is a mixture of a fluorocarbon-based gas and oxygen gas; and a step of peeling off the remaining resist mask 13 using a chemical liquid. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to, for example, a method for forming an organic film pattern applied to the formation of an organic film which is a constituent element of a solid-state image pickup device, and a solid-state image pickup device using this organic film pattern formation method. Manufacturing method.

[0002]

2. Description of the Related Art For example, in a structure of a solid-state image pickup device composed of a semiconductor, there are some constituent elements formed of an organic film. For example, a color filter, an on-chip microlens, a flattening film, an insulating layer of a multilayer wiring board, and the like. In the recent era of miniaturization of solid-state image sensors and higher pixel count, the establishment of a process for processing an organic film by dry etching is based on the use of various organic films in future miniaturization of solid-state image sensors. It can be a technology with a very wide range of applications. Many processes have been proposed as a method of processing the above organic film.
In these general processes, processing is performed by a lithographic process using a photosensitive organic film material. In addition, an organic film pattern may be formed by using a lift-off method together with an etching process typified by dry etching.

FIG. 5 shows an outline of an etching process of a so-called organic film using a photoresist in a conventional semiconductor manufacturing process. First, as shown in FIG. 5A, a base organic film 2 to be patterned is formed on a semiconductor substrate 1. The organic film 2 includes, for example, a color filter, a flattening film, and the like. Next, as shown in FIG. 5B, for example, a positive type photoresist film 3 is applied on the organic film 2 using a spinner. Next, the photoresist film 3 is exposed by the exposure device through the optical mask 4 having a required mask pattern. After the exposure, a development process is performed using an alkaline developing solution to form a photoresist pattern 5 as shown in FIG. 5C. Next, FIG.
As shown in D, the semiconductor substrate 1 on which the photoresist pattern 5 is formed on the organic film 2 is placed in a vacuum container, and an oxygen gas simple substance O ₂ or an oxygen gas and a fluorocarbon-based gas CF ₄ is mixed. A mixed gas or the like is introduced, plasma is generated, and dry etching is performed from the opening 5A of the photoresist pattern 5 to the underlying organic film 2
Are removed by etching. Then, this semiconductor substrate 1 is installed in an ashing device, and oxygen gas plasma is introduced to perform an ashing process to completely remove the photoresist pattern 5 as an extra etching mask. Alternatively, the photoresist pattern 5 is removed with a photoresist stripping solution (see FIG. 5E).

Further, as a method for patterning the organic film 2, exposure using an organic film containing a photosensitive material,
It is also possible to apply a method of performing a predetermined patterning through the development process.

In general, the above-mentioned dry ashing process removes a photoresist made of an organic polymer on a semiconductor substrate by burning reaction on the photoresist surface by a radical factor of oxygen to generate CO and CO _2. Going is the basic concept of the process. As a condition for ashing, the temperature of the semiconductor substrate for securing the ashing rate is often set to a high temperature of about 200 ° C. to 280 ° C. because the oxidation reaction by radicals affects the temperature of the semiconductor substrate. Further, as for the usual photoresist stripping, the photoresist can be stripped sufficiently well by an ashing process using only oxygen gas O ₂ .

In the above process, a hardened layer is formed near the resist surface exposed to the plasma atmosphere during dry etching. This is because the hydrogen atoms in the organic polymer are released by the impact of ions, resulting in a complex cross-linked structure of the organic polymer, or because the crosslinking reaction proceeds near the resist film surface due to heat. It is believed to be a formed layer. The ashing rate of the layer near the resist surface is assured at a high temperature of 200 ° C. or higher, but at 200 ° C. or lower, the reaction rate between oxygen radicals and the resist surface is slow and the ashing rate hardly occurs.

However, it is known that when ashing is performed at a high temperature of 200 ° C. or higher, the uncured resist under the cured layer expands, the internal pressure increases, and a popping phenomenon occurs to generate particles. These particles are attempted to be removed by a method using a stripping solution or the like, but they cannot be completely removed, which causes deterioration of device performance.

[0008] As a method of solving the influence of this cured layer, reactive ion etching with the addition of H ₂ gas (RI
E) was devised. Thus, it has been proposed to remove the hardened photoresist surface layer and then remove the photoresist by ashing oxygen plasma gas. However, this method requires a long time for the RIE treatment of H ₂ gas, and a decrease in throughput during production is expected. Therefore, this method is not very effective.

Another problem solving method described above is disclosed in Japanese Patent No. 319.
Proposed in 8667 and Japanese Patent No. 3218722. As in the prior art, the base film is etched using the photoresist as an etching mask by dry etching using oxygen plasma gas. After that, set the substrate temperature to 2
This is a method in which the photoresist is removed by ashing with an oxygen plasma gas to which a reducing gas such as a fluorine (F) -based gas or a hydrogen (H) -based gas is added at a high temperature of around 00 ° C. This is because the introduction of fluorine or hydrogen during ashing removes hydrogen atoms by dry etching, weakens the bonds that crosslink the molecular structure, and promotes the ashing reaction. This has the advantage that no particle residue is generated.

In Japanese Patent No. 3198667, COF, SOF ₂ and NOF, or a gas containing hydrogen atoms, H ₂ O gas and NH ₃ gas may be added to these gases as this type of reducing gas. A gas containing hydrogen atoms, such as H ₂ O gas or NH ₃ gas, may be added to CO, NO ₂ , and SO ₂ . Further, it has been proposed to use a gas containing H ₂ , H ₂ O, NH ₃ containing hydrogen atoms and F atoms as a reducing gas of CO, NO ₂ and SO ₂ . Patent No. 3
No. 218722, another method is ashing treatment followed by sulfur fluoride such as S ₂ F ₂ , SF ₂ , SF ₄ ,
A plasma treatment including a gas containing at least one of S ₂ F ₁₀ and oxygen O _2, and a method of adding H ₂ or H ₂ O to the plasma treatment and performing a plasma treatment to remove the oxygen have also been proposed.

Apart from these, the ashing process is performed in two stages.
The method of dividing into two is disclosed in Japanese Patent Laid-Open No. 2000-231202 or a special method.
Some have been proposed in Kaihei 5-275326 and the like.
Contents proposed in Japanese Patent Laid-Open No. 2000-231202
Using oxygen plasma gas as the ashing gas,
The temperature at the time of removing the resist surface hardening layer of
Less than 0 ° C, and process temperature in the latter half is 150 ° C or higher and 250
Remove resist by ashing below ℃
Is the way to do it. Proposed in Japanese Patent Laid-Open No. 5-275326
The contents of the oxygen gas O in the initial stage of ashing₂
And a gas containing fluorine, such as CF_FourAnd NF₃, S
F₆, C_FourF ₈Remove the hardened layer by using either of the
After that, the photoresist under the cured layer is exposed to oxygen plasma.
It is a method of removing by ashing.

In contrast to the above method, there is a method in which an inorganic film is used as an etching mask instead of a photoresist, so that the underlying organic film is patterned in a predetermined manner without using ashing.
And Japanese Patent Laid-Open No. 4-234706. The content proposed in JP-A-59-146005 is that a predetermined pattern opening is formed by exposing a chalcogen glass layer on an organic film, and then the chalcogen glass layer is used as an etching mask to form an organic underlayer. This is a method of patterning by dry-etching the film using a gas mainly containing oxygen. The contents proposed in Japanese Patent Laid-Open No. 4-234706 are the following methods. A color filter layer on the substrate, a Si-containing barrier layer thereon,
A photoresist layer is sequentially formed. Next, after forming a predetermined pattern on the photoresist, the barrier layer exposed in the resist pattern opening is etched by the first reactive ion etching containing a fluorine compound. Next, the filter layer exposed in the barrier layer opening is etched by the second reactive ion etching containing oxygen to form a pattern in the filter layer. This method is characterized by etching the barrier layer by the first etching and etching the photoresist layer and the filter layer by the second etching.

[0013]

As described above, when a photoresist is used as an etching mask, the hardened layer on the resist surface exposed in the plasma atmosphere poses a problem. However, when considering removing all the photoresist on the organic film by ashing by the conventional method, only the photoresist is completely removed because the organic film underlying the photoresist of the etching mask is the same organic film as the photoresist. It is difficult to remove ashing. Because
This is because the above ashing process also removes the organic film by the combustion reaction. Therefore, it is difficult to completely remove the photoresist by burning reaction by the ashing process, and at the same time, the underlying organic film itself is considerably ashed, and the organic film of a predetermined pattern is obtained by ashing from the side wall opened by the pattern. Is difficult

A method of forming an inorganic substance on the organic film as an etching mask is also considered. However, when attempting to peel off this inorganic substance, an organic film is deposited on the inorganic substance as a by-product when the underlying organic film is etched, and as a result, the organic deposited film hinders peeling of the inorganic substance. Therefore, the organic deposition film on the inorganic material is removed by performing an ashing process mainly containing oxygen gas. Then, the inorganic substance is peeled off with a chemical solution. As described above, after the organic deposited film is removed, it is necessary to remove the inorganic substance with the chemical liquid, which increases the number of steps during processing. In addition, since an acid is used as a chemical for peeling off an inorganic substance, it may affect the properties of the underlying organic film and change the properties of the organic film. In addition, it is considered that the use of this process at the manufacturing site of the product has a bad influence on the global environment.

Consider a case where the etching mask formed on the organic film is applied to a device without peeling, and a case where a film to be an etching stopper layer is inserted between layers.
At this time, the transmittance of the organic film is required to be transparent in the required wavelength range of light, or physically or chemically resistant to etching gas or ashing gas is required, If the stripper is required to have chemical resistance, many restrictions will occur, which is not suitable for process application.

A method in which the photoresist ashing process is precisely controlled and stopped at the surface of the underlying organic film is also considered. However, also in this respect, it is impossible at this stage to uniformly remove only the photoresist due to the non-uniformity of the plasma density of etching and ashing in the chamber. Even if only the photoresist can be removed with high precision control, it is estimated that the reaction of the ashing gas and the surface of the organic film may change the transmittance of the organic film itself, the film quality, or the pattern. .

In view of the above points, the present invention uses a solution that removes only the surface hardened layer by ashing and then dissolves only the photoresist to reduce the physical and optical burdens on the underlying organic film and photo The present invention provides a method for forming an organic film pattern that enables the formation of a favorable organic film pattern by removing a resist, and a method for manufacturing a solid-state image sensor using the method for forming an organic film pattern.

[0018]

A method of forming an organic film pattern according to the present invention comprises a step of forming an organic film on a substrate,
The method includes a step of patterning an organic film by etching through a resist mask, a step of ashing and removing a hardened layer on the surface of the resist mask by plasma gas, and a step of peeling the remaining resist mask using a chemical solution.

According to the method for forming an organic film pattern of the present invention, since the organic film is etched through the resist mask and the ashing process is performed with the plasma gas, the hardened layer on the surface of the resist mask can be completely removed. After that, the remaining resist mask is peeled off using a solvent,
The resist mask is peeled off without residue, and does not physically or optically affect the underlying organic film, that is, without changing the film quality of the organic film itself, changing the pattern, changing the transmittance, etc. The organic film can be patterned.

The method of manufacturing a solid-state image pickup device according to the present invention comprises:
A color filter or / and a bonding pad portion is formed by using the above-described method of forming an organic film pattern. That is, a first step of forming an organic film for a filter on the image pickup region where the light receiving pixel is formed, and patterning the organic film by dry etching with a plasma gas containing oxygen as a main component through a resist mask; A second step of forming a first color filter component pattern by ashing and removing the hardened layer on the surface of the resist mask with a plasma gas in which a system gas and an oxygen gas are mixed, and peeling the remaining resist mask with a chemical solution. ,Less than,
A resist mask is formed on a predetermined region, an organic film for a filter is formed on the entire surface including the resist mask, and then a third step of peeling off the resist mask and the organic film thereon, and the organic film After the fourth step of patterning by dry etching through a resist mask, and removing the hardened layer on the surface of the resist mask by ashing with a plasma gas in which a fluorocarbon-based gas and an oxygen gas are mixed, a chemical solution is applied to the remaining resist mask. The fifth step of peeling using is repeated, and the final step is the third step.
As a process, filter component patterns for the second and subsequent colors are formed to form color filters. Further, in forming the bonding pad portion, a step of forming a bonding pad portion on the semiconductor substrate on which the light receiving pixels are formed, forming a flattening film made of an organic film to cover the bonding pad portion, and a flattening film. Patterning by dry etching with a plasma gas containing oxygen as a main component through a resist mask to expose the bonding pad portion to the outside, and a plasma gas that is a mixture of a fluorocarbon gas and an oxygen gas. The method includes a step of ashing and removing the hardened layer, and a step of peeling the remaining resist mask with a chemical solution.

In the method for manufacturing a solid-state image pickup device of the present invention, since the above-described organic film pattern forming method is used, the resist mask used for patterning is completely removed without producing a residue, and physical and optical influences are exerted. Without this, it is possible to form a good color filter with high accuracy, or to form a flattening film pattern with the bondin pad portion exposed to high accuracy.

[0022]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows an embodiment of a method for forming an organic film pattern according to the present invention. First, as the first step,
As shown in FIG. 1A, the organic film 12 is formed on the semiconductor substrate 11. The organic film 12 is formed by using, for example, a vacuum vapor deposition method or a coating method. In the second step, as shown in FIG. 1B, a photoresist layer, in this example, a positive photoresist layer 13 is applied on the organic film 12 formed on the semiconductor substrate 11 to form a predetermined film thickness. After that, the photoresist layer 13 is exposed using an exposure mask having a predetermined pattern, in this example, an exposure mask having a predetermined opening. Then, as shown in FIG. 1C, the exposed photoresist layer 13 is subjected to a developing treatment to
A resist pattern having the required openings 14 is formed. The opening 14 of the exposure mask corresponds to the region where the organic film 12 should be removed, and the resist layer 13 exists only in the region where the pattern of the organic film 12 is desired to be formed.

In the third step, as shown in FIG. 1D, a microwave plasma etching apparatus in which oxygen plasma is introduced using the resist layer 13 as a mask is used to dry-etch the organic film 12 into a predetermined pattern formed of photoresist. Then, a predetermined organic film pattern 120 similar to the pattern of the resist layer 13 is formed. The etching condition is that the wafer stage temperature is room temperature (20 ° C).
It is set on a cooled wafer stage below, and an etching gas containing oxygen O ₂ as a main component is used.
If the wafer stage temperature is higher than room temperature (20 ° C.), not only the thermal curing of the resist due to plasma during etching but also the thermal curing of the resist due to the substrate temperature becomes significant. As a result, the hardened layer becomes thick, and it becomes difficult to remove the resist by ashing. When the stage temperature is set to a low temperature (for example, -50 ° C or lower), a side wall protective film (mainly a polymer film formed in plasma) is easily formed during etching, which may cause difficulty in removing the resist by ashing treatment. Become. The film thickness of the resist layer 13 is sufficient to withstand the etching of the organic film 12. Therefore, the resist layer 13 is not completely removed during the etching of the organic film 12. Dry etching is performed by, for example, microwave plasma etching (microwave frequency: 2.45 GMH.
This is anisotropic etching using z), and it is possible to form a pattern of the organic film 12 having a vertical cross section. In addition, the cross-sectional shape after etching can be controlled by changing the flow rate ratio of the oxygen gas O ₂ . During the dry etching of the organic film 12, a hardened layer 15 is formed on the surface of the resist layer exposed to the plasma atmosphere.

In the fourth step, as shown in FIG.
After the etching, the ashing process is performed while maintaining the vacuum state.
The process is continuously performed, and the vicinity of the resist layer surface is about 80 nm.
Then, the hardened layer 15 is removed. The ashing process is
Luoro carbon type gas CHF ₃And oxygen O₂Mixed
Performed by plasma gas. The ashing condition is CHF₃When
O₂Flow rate ratio (CHF₃/ O₂Ratio) 1.0 to 5.0%
Do it. At this time, the total flow rate of CHF₃Increase the flow rate of
It was confirmed that the ashing speed increased when added.
It was If the above flow rate ratio is less than 1.0%, the ashing speed
Slows down and the ashing process takes a long time. 5.0%
If there is more than this, the ashing speed becomes too fast, so
It becomes difficult to control the singing process. Ashing
The temperature of the semiconductor substrate 11 is about 10 ° C to 30 ° C at room temperature.
Can be

In the fifth step, as shown in FIG. 1F, only the resist layer 13 on the organic film 12 is stripped with a stripping solution. For the stripping solution, MMP (methyl-3-methoxypropionate) thinner, EL (ethyl lactate) thinner, E
It is possible to use a mixed solution of L and butyl acetate, or an organic solvent such as acetone. A predetermined organic film pattern 120 is formed by this process. The stripping solution used here is one that melts only the resist layer 13 and does not react with the organic film 12.

According to the present embodiment, through the steps described above, the organic film 12 can be dry-etched to a predetermined pattern, and a predetermined organic film pattern 120 can be formed. It becomes possible to realize fine processing. After the dry etching using oxygen gas, the vicinity of the resist mask surface is removed by about 80 nm by plasma ashing treatment using fluorocarbon gas and oxygen gas, so that the hardened layer 15 on the resist mask surface can be completely removed. After that, since the remaining resist mask is peeled off using an organic solvent, the resist mask is peeled off without residue, and does not adversely affect the underlying organic film pattern 120, that is, the change in the film quality of the organic film pattern itself, the change in the pattern, The organic film can be accurately patterned without causing a change in transmittance or the like. In dry etching, room temperature (20
Since the substrate is placed on a stage cooled to a temperature of (.degree. C.) or less and the organic film 12 is dry-etched, the resist can be removed well in the subsequent ashing process.

Next, an example of another embodiment to which the above-described organic film pattern forming method is applied will be described.

2 to 3 show a form of an embodiment in which the present invention is applied to manufacture of a solid-state image pickup device, particularly to formation of a color filter thereof. First, as shown in FIG. 2A, an organic vapor deposition film 22 for a first color having a prescribed color component is uniformly formed on the surface of a semiconductor substrate 21 on which a plurality of light receiving pixels are formed by using a vacuum vapor deposition method. It is formed so as to be distributed in.

Next, as shown in FIG. 2B, the semiconductor substrate 2
On the organic vapor deposition film 22 formed on No. 1, a photoresist, in this example, a positive type photoresist, is used to apply a photoresist layer 23 to a predetermined thickness. For this photoresist, for example, product name HPR204 (manufactured by Fuji Film Arch Co., Ltd.) can be used. Thereafter, the resist layer 23 is exposed using an exposure mask corresponding to the first color filter component pattern (that is, the organic film pattern), in this example, an exposure mask having a predetermined opening corresponding to the first color filter component pattern. Then, the exposed resist layer 23 is developed to form the pattern openings 24. The opening of the exposure mask corresponds to the region where the organic vapor deposition film 22 is to be removed, and the resist layer 23 exists only in the region where the filter component pattern of the first color is desired to be formed.

Next, as shown in FIG. 2C, the resist layer 2
Using the microwave plasma etching apparatus using oxygen plasma with 3 as a mask, the organic vapor deposition film 22 is patterned by dry etching to form the filter component pattern 220 of the first color. This dry etching is performed by microwave etching (microwave frequency: 2.45 GM).
It is anisotropic etching using (Hz), and a pattern of the organic vapor deposition film 22 having a vertical cross-sectional shape can be formed. As the etching conditions, for example, the sample is set on the wafer stage in which the wafer stage temperature is set to about −30 ° C., oxygen O ₂ flow rate: 100 sccm, RF power:
Perform at 0W. During the dry etching of the organic vapor deposition film 22, a hardened layer 25 is formed on the surface of the resist layer exposed to the plasma atmosphere.

Next, as shown in FIG. 2D, ashing treatment is continuously performed in a vacuum state after dry etching to remove the hardened layer 25 by removing about 80 nm near the surface of the resist layer 23. The ashing step is performed by mixing the fluorocarbon gas CHF ₃ and the oxygen gas O ₂ . The conditions are, for example, that the temperature of the semiconductor substrate is room temperature (eg
At 0.7 ℃), CHF ₃ flow rate: 10~40sccm, O
The total flow rate of ₂ + CHF ₃ was 840 sccm, and the asher pressure during ashing was 100 Pa. Total flow rate CH
When the flow rate ratio of F ₃ is increased, the ashing speed tends to increase.

Next, as shown in FIG. 2E, only the resist layer 23 on the organic vapor deposition film 22 is peeled off by a peeling solution. As the stripping solution, it is possible to use an organic solvent such as MMP thinner, EL thinner, a mixed solution of EL and butyl acetate, or acetone. Through the steps so far, the resist layer 23 is completely removed, and there is no resist residue on the surface.
The color filter component pattern 220 can be formed. The stripping solution used here must be one that melts only the resist layer 23 and does not react with the organic vapor deposition film 22.

Next, a filter component pattern for the second color or less (that is, an organic film pattern) is formed. As shown in FIG. 2F, a resist pattern in which the resist layer 23 remains only on the first color filter component pattern 220 is formed, and then the second color organic vapor deposition film different from the first color organic vapor deposition film 22 is formed on the entire surface. The film 26 is formed by a vapor deposition method. After that, as shown in FIG. 3G, the resist layer 23 is stripped together with the organic vapor deposition film 26 thereon by using an appropriate stripping solution.

After that, the same steps as described above are repeated.
As shown in FIG. 3H, the resist layer 23 is left over the first color filter component pattern 220 and the second color organic vapor deposition film 26 except for the region where the third color filter component pattern is to be formed. Thus, a resist pattern is formed. Next, as shown in FIG. 3I, the organic vapor deposition film 26 is selectively etched away by dry etching using a microwave plasma etching apparatus using oxygen plasma with the resist layer 23 as a mask, and a second color filter component pattern is formed. Forming 260.

Next, as shown in FIG. 3J, in the same manner as above, the ashing process is continuously performed to remove the hardened layer on the surface of the resist layer 23, and then only the resist layer 23 is peeled by a peeling liquid. In this way, the second color filter component pattern 260 is formed.

Next, as shown in FIG. 3K, the first color and the second color
After forming a resist pattern in which the resist layer 23 remains only on the filter component patterns 220 and 260 of the color,
As shown in FIG. L, an organic vapor deposition film 27 for the third color, which is different from the organic vapor deposition films 22 and 26 for the first color and the second color, is formed on the entire surface by the vapor deposition method.

Next, the resist layer 23 is peeled off together with the organic vapor-deposited film 27 thereon by using an appropriate peeling liquid to form a third color filter component pattern 270. In this way, as shown in FIG. 3M, the color filter layer 28 of the target solid-state imaging device is obtained.

In the above example, the present invention is applied to the formation of a color filter composed of filter components of three colors, but it is also possible to form a color filter composed of filter components of four or more colors by repeating the same steps.

According to the method of manufacturing a solid-state image sensor according to the present embodiment, particularly the method of forming a color filter, the resist mask 23 used in patterning is not damaged, without damaging the underlying filter component patterns 220, 260, 270.
Can be completely removed, and a good color filter 28 can be formed. Therefore, it is possible to reduce the size of the solid-state image sensor and increase the number of pixels.

FIG. 4 shows a form of an embodiment in which the present invention is applied to the manufacture of a solid-state image pickup device, particularly to the formation of a bonding pad portion thereof. First, as shown in FIG. 4A,
On the surface of the semiconductor substrate 31 in which a plurality of light receiving pixels are formed in the image pickup region 32, the color filter layer 33 made of a prescribed color component is formed. In addition, the imaging region 3 on the semiconductor substrate 31
A bonding pad portion 34 made of a conductive film is formed in the peripheral portion of 2. After that, a flattening film 35 made of an organic film is formed on the entire surface including the color filter layer 33 and the bonding pad portion 34, and further made of a styrene-based organic film on the flattening film 34 so as to correspond to each light receiving pixel. The on-chip microlens 36 is formed.

Next, as shown in FIG. 4B, for example, a positive type photoresist layer 37 is applied to the surface of the substrate including the on-chip microlenses 36 so as to have a predetermined film thickness. This photoresist layer 37 is, for example, a product name:
IX305 (manufactured by JSR Corporation) can be used.

Next, the photoresist layer 37 is exposed and developed using a required exposure mask, for example, an exposure mask having an opening at a position corresponding to the bonding pad portion 34, and as shown in FIG. 4C. Bonding pad part 3
A resist layer 37 having a predetermined pattern having an opening 37A is formed in a portion corresponding to 4. That is, the opening of the exposure mask corresponds to the region where the flattening film 35 made of an organic film is to be removed, and the resist layer 37 after exposure and development wants to expose the bonding pad portion 34 on the flattening film 35. Does not exist only in the area.

Next, as shown in FIG. 4D, the resist layer 3
Using the ECR plasma etching apparatus using oxygen plasma gas with 7 as a mask, the flattening film 35 made of an organic film is patterned by dry etching. As a result, the flattening film pattern 350 having the opening 35A facing the pattern of the predetermined bonding pad is formed.
This dry etching is anisotropic etching using microwave plasma etching (microwave frequency: 2.45 GHz), and a flattening film pattern 350 made of an organic film having a vertical cross section can be formed. The etching conditions are, for example, a wafer stage temperature of -30.
C., O ₂ flow rate: 100 sccm, RF power: 0 W. At this time, when the RF power is increased, the etching cross section of the organic film tends to be vertical.

Next, after dry etching, ashing treatment in a vacuum state is continuously performed to remove the surface of the resist layer 37 by 8 times.
About 0 nm is removed, and the hardened layer 38 on the surface of the resist layer is removed. Ashing is fluorocarbon gas CHF ₃
And oxygen gas O ₂ are mixed. The conditions are semiconductor substrate 3
The temperature of 1 is room temperature (20.7 ° C. in this example), the CHF ₃ flow rate is 10 to 40 sccm, and the total flow rate of O ₂ + CHF ₃ is 8
It is carried out at 40 sccm and an asscher pressure of 100 Pa.
The ashing rate tends to increase as the CHF ₃ flow rate ratio of the total flow rate increases.

Next, as shown in FIG. 4E, only the resist layer 37 on the flattening film 35 made of an organic film is removed with a removing solution. As the stripping solution, it is possible to use an organic solvent of a mixed solution of EL thinner and butyl acetate. As a result, it becomes possible to form the flattening film pattern 350 of the organic film having the opening 35A facing the bonding pad portion 34. The stripper used here is the resist layer 3
A material that melts only 7 and does not react with the on-chip microlens 36 made of an organic film or the flattening film 35 is selected.
In this way, a solid-state image sensor having the accurate flattening film pattern 350 and the bonding pad portion 35 exposed to the outside is obtained. The solid-state image sensor manufactured in this way does not show a characteristic change from the solid-state image sensor manufactured in the conventional process.

According to the method of manufacturing the solid-state image sensor according to the present embodiment, particularly the method of forming the bonding pad portion thereof, after patterning the flattening film 35, the resist mask 23 is formed without damaging the underlying flattening film 35. Can be completely removed. Then, the opening 35A of the flattening film 35
Therefore, the fine bonding pad portion 34 can be exposed. Therefore, it is possible to reduce the size of the solid-state image sensor and increase the number of pixels.

[0048]

According to the method of forming an organic film pattern according to the present invention, after the organic film is patterned by etching through the resist mask, plasma ashing treatment is performed, and then the resist mask is formed by using a chemical solution. By peeling, only the resist mask used as the etching mask can be easily peeled without a residue.
Therefore, good organic film patterning can be formed.

In the dry etching step, the temperature of the stage on which the sample is set is set to 20 ° C. or lower, whereby the resist can be removed well in the subsequent ashing process. When the ashing process is performed at a substrate temperature of 10 ° C. to 30 ° C., the process is performed at a so-called normal temperature, so that it is not necessary to return the temperature to the normal temperature thereafter, and the processing time and cost can be reduced. When the remaining resist mask is stripped using the organic solvent, the organic solvent has selectivity, so that only the resist mask can be removed without affecting the underlying layer. Since the etching cross-sectional shape of the organic film is controlled by controlling the etching conditions, the etching cross-section of the organic film can be made vertical.

In the ashing process, the vicinity of the surface of the resist mask including the hardened layer is removed by ashing, so that the hardened layer can be surely removed. The flow rate ratio of the fluorocarbon gas in the plasma gas during the ashing process is 1
By adjusting the ashing rate to ~ 5%,
Good ashing processing becomes possible. Further, only the resist mask on the organic film can be reliably peeled off by selecting the chemical solution, that is, the organic solvent.

According to the method of manufacturing a solid-state image sensor according to the present invention, by using the above-described method for forming an organic film pattern, color filters and bonding pad portions of the solid-state image sensor, which are required to have high pixel count and high sensitivity. It is possible to provide a solid-state image sensor having high reliability.

[Brief description of drawings]

1A to 1F are process charts showing an embodiment of a method for forming an organic film pattern according to the present invention.

2A to 2F are process drawings (No. 1) showing another embodiment in which the method for forming an organic film pattern according to the present invention is applied to the formation of a color filter of a solid-state imaging device.

FIG. 3 is a process diagram (No. 2) showing another embodiment in which the method for forming an organic film pattern according to the present invention is applied to the formation of a color filter of a solid-state image sensor.

4A to 4E are process diagrams showing another embodiment in which the method for forming an organic film pattern according to the present invention is applied to the formation of a bonding pad portion of a solid-state image sensor.

5A to 5E are process drawings showing a method of forming an organic film pattern according to a conventional example.

[Explanation of symbols]

11 ... Semiconductor substrate, 12 ... Organic film, 13 ...
Photoresist layer, 15 ... Cured layer, 120 ... Organic film pattern, 21 ... Semiconductor substrate, 22 ... First color organic film, 23 ... Photoresist layer, 24 ...
-Opening, 25 ... Cured layer, 220 ... First color filter component pattern, 26 ... Second color organic film, 26
0 ... second color filter component pattern, 27 ... 3
Colored organic film, 270 ... Third color filter component pattern, 28 ... Color filter, 31 ... Semiconductor substrate, 32 ... Imaging region, 33 ... Color filter, 34 ... Bonding Pad, 35 ... Flattening layer, 36 ... On-chip microlens, 37 ...
Photoresist layer, 38 ... Hardened layer, 350 ... Planarization film pattern

   ─────────────────────────────────────────────────── ─── Continued front page    F term (reference) 2H096 AA25 HA23 HA30 JA04 LA02                 4M118 AA01 EA18 EA20 GC07                 5F004 AA05 BB14 BD01 CA02 CA04                       DA16 DA26 DB00 DB26 EA10                       FA08                 5F046 MA12

Claims (10)

[Claims] 1. A step of forming an organic film on a substrate, a step of patterning the organic film by etching through a resist mask, a step of ashing and removing a hardened layer on the surface of the resist mask by plasma gas, and a chemical solution. And a step of removing the remaining resist mask by using. 2. The etching according to claim 1, wherein the etching is dry etching using a plasma gas containing oxygen as a main component, and the substrate is placed on a stage cooled to 20 ° C. or lower for etching. Method for forming organic film pattern. 3. The method for forming an organic film pattern according to claim 1, wherein the ashing treatment is performed at a substrate temperature of 10 ° C. to 30 ° C., and the resist mask is stripped using an organic solvent. 4. The method for forming an organic film pattern according to claim 1, wherein the etching cross-sectional shape of the organic film is controlled by controlling the etching conditions. 5. The method for forming an organic film pattern according to claim 1, wherein the ashing process is performed under ashing conditions in which no residue is generated after the resist mask is peeled off. 6. The ashing removal is performed near the surface of the resist mask including the hardened layer.
A method for forming an organic film pattern as described. 7. A flow rate ratio of fluorocarbon gas is 1 to 5
The method for forming an organic film pattern according to claim 1, wherein the ashing treatment is performed by using the plasma gas containing 100% by weight. 8. The method for forming an organic film pattern according to claim 1, wherein only the resist mask is removed with an organic solvent that does not affect the organic film. 9. A first step of forming an organic film for a filter on an image pickup region where a light receiving pixel is formed, and patterning the organic film by dry etching with a plasma gas containing oxygen as a main component through a resist mask. And a cured gas layer on the surface of the resist mask is removed by ashing with a plasma gas in which a fluorocarbon-based gas and an oxygen gas are mixed, and then the remaining resist mask is peeled off using a chemical solution to form a first-color filter component pattern. 2 steps, hereinafter, a third step of forming a resist mask on a predetermined region, forming an organic film for a filter on the entire surface including the resist mask, and then peeling off the resist mask and the organic film thereon And a fourth step of patterning the organic film by the dry etching through a resist mask, and The fifth step of ashing and removing the hardened layer on the surface of the resist mask using a plasma gas in which a carbon-based gas and an oxygen gas are mixed, and then peeling the remaining resist mask with a chemical solution is repeated, and the final step is the third step. A method for manufacturing a solid-state image sensor, comprising forming a filter component pattern for a second color or later and forming a color filter as a step. 10. A step of forming a bonding pad portion on a semiconductor substrate on which a light receiving pixel is formed, forming a planarizing film made of an organic film to cover the bonding pad portion, and using the planarizing film as a resist mask. Patterning by dry etching with a plasma gas containing oxygen as a main component to expose the bonding pad portion to the outside, and hardening of the resist mask surface with a plasma gas that is a mixture of fluorocarbon gas and oxygen gas. A method for manufacturing a solid-state imaging device, comprising: a step of removing a layer by ashing; and a step of peeling the remaining resist mask using a chemical solution.