JPH09244249A - Pattern forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a pattern forming method by which the adhesion of constituent layers is improved and resolution is improved. SOLUTION: A desired pattern is formed using a substrate to be worked, an adhesion improving layer and a resist material layer. The adhesion improving layer is a layer of a spin-on-glass(SOG) material represented by the formula Rn Si(OH)4-n [where R is at least one kind of group selected from among satd. aliphatic hydrocarbon, unsatd. aliphatic hydrocarbon and cyclic satd. hydrocarbon and (n) is an integer of 1-3] and having one or more silanol groups (Si-OH). Heat treatment is preferably carried out after coating with the SOG material layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an X-axis on a substrate to be processed used for processing LSIs, micromachines and the like.
A resist material layer having sensitivity to energy rays such as rays, ultraviolet rays, and electron rays is coated, selectively irradiated with the energy rays, and further developed to form a resist pattern having a desired shape. The present invention relates to an improvement in a pattern forming method for performing a selective processing process on an object to be processed using the resist pattern as a mask.

[0002]

2. Description of the Related Art A conventional pattern forming method for a substrate to be processed in manufacturing an LSI and a micromachine will be described below. First, in LSI manufacturing, for example, in order to form a fine pattern on a silicon substrate that is a workpiece having a silicon oxide film formed on its surface, hexamethyldisilazane (hereinafter,
(Abbreviated as HMDS), and X-rays on the adhesion enhancing material.
A resist material layer having sensitivity to energy rays such as ultraviolet rays and electron rays is coated, selectively irradiated with the energy rays, and further developed, rinsed, and dried.
A pattern forming method has been used in which a resist pattern having a desired shape is formed and a selective processing is performed on an object to be processed using the resist pattern as a mask. The HM
The coating of the DS is performed by exposing the work piece in a vapor atmosphere of HMDS for coating, and the film thickness is 0.01 to 0.
It is 03 μm. As a method for selectively processing the object to be processed, a dry etching method such as ion etching, reactive sputter etching, and plasma etching is mainly used with the resist pattern as a mask. HM between resist pattern and workpiece
Since the film thickness of HMDS is extremely thin, DS is removed simultaneously with the processing of the object to be processed. As a method of coating the resist material on the adhesion enhancing material, in the case of an LSI requiring a thin film of about 1 μm, a method of coating a liquid resist material by spin coating is generally used. On the other hand, in micromachine manufacturing, in order to form a fine pattern on a silicon substrate, which is a workpiece whose surface is coated with a copper film, for example, HMDS is coated on the workpiece substrate as an adhesion enhancing material, and the adhesion enhancing material is applied. Then, a resist material layer having sensitivity to energy rays such as X-rays, ultraviolet rays, and electron rays is coated on the surface, selectively irradiated with the energy rays, and further developed, rinsed, and dried to obtain a desired shape. Selective processing of an object to be processed by a so-called micromachine process of forming a resist pattern having, forming a conductor pattern by selectively electroplating a new conductor material on the copper film using the resist pattern as a template A pattern forming method of performing processing is used. As a method of coating the resist material on the adhesion enhancing material, 1
For a resist manufactured by a micromachine, which requires a thick film of 0 μm or more, a method is generally used in which a film-shaped resist material, that is, a so-called dry film is placed on a workpiece and adhered and coated by heat treatment.

An aspect ratio (hereinafter referred to as "T") which is a ratio of a resist film thickness (hereinafter referred to as "T") to a pattern size (hereinafter referred to as "S") in manufacturing the LSI and micromachines.
The abbreviation A, A = T / S) is increasing year by year. This is because, in the former LSI process technology, the film thickness of the resist material required at the time of etching is not so much reduced, although the pattern size tends to be significantly reduced. In other words, the film thickness of the resist material is required to have sufficient resistance when etching the object to be processed, and is required because the film thickness of the object to be processed does not decrease as the pattern size tends to decrease. The above-mentioned A becomes large. On the other hand, even in the latter micromachine process technology, in order to obtain sufficient conductivity and strength with a fine pattern, there is adopted a method of increasing the resist film thickness to increase the volume of copper. Therefore, it is necessary to increase A above. . That is, although the processes are different, large A is required for both LSI and micromachine manufacturing.

[0004]

In LSI manufacturing, when A of the resist pattern is increased, the force applied to the adhesive surface between the resist pattern and the workpiece during development is increased, which causes the resist pattern to separate from the workpiece. Became. Further, in micromachine manufacturing, if A of the resist pattern is increased, in addition to the pattern peeling phenomenon at the time of development, the plating solution penetrates into the bonding surface between the resist pattern and the substrate to be processed in the step of plating the conductive material, This is a factor that the conductive material is plated on the permeated portion and the resist pattern is peeled off during the plating. An object of the present invention is to provide a pattern forming method that solves the above problems.

[0005]

The present invention will be described in brief. The present invention relates to a pattern forming method, in which a desired pattern is obtained by a substrate to be processed, an adhesion enhancing material layer, and a resist material layer. In the forming method, as the adhesion enhancing material layer, a general formula: R _n Si (OH) _4-n (wherein R is a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, or a cyclic saturated hydrocarbon group) is used. (At least one group selected from the group consisting of n and n is an integer of 1, 2, or 3)
A spin-on-glass (hereinafter abbreviated as SOG) material layer containing at least one silanol group (Si—OH) represented by is used.

In the above-described LSI of the present invention and the method for processing a substrate to be processed in micromachine manufacturing, in order to enhance the adhesion, it is necessary to use two means having a high adhesion enhancing effect in combination. That is, as the first solving means, by providing an adhesion enhancing material for enhancing the adhesion between the workpiece substrate and the resist material layer, as the second solving means, the first solving means It is to provide a resist material having high adhesion to an adhesion enhancing material. Therefore,
The present inventors use an SOG material layer represented by the general formula: R _n Si (OH) _{4 -n} as an adhesion enhancing agent as an adhesion enhancing material layer for solving the first problem, and As a resist material layer for solving the second problem, O is formed in the resist material layer or on the surface of the resist material layer.
The inventors have found that the use of a resist material layer containing an H group makes it possible to form a resist pattern having a high adhesiveness and a large A, and has completed the present invention.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be specifically described below. First, as described above, it is preferable to use a resist material layer containing an OH group in the resist material layer or on the surface of the resist material layer as the resist material layer. As the resist material layer, a resist material layer containing an OH group in the resist material layer or on the surface of the resist material layer, and the SOG described above as the adhesion enhancing material layer
Preference is given to using layers in combination with material layers. Said S
It is also preferable to include a heat treatment step after coating the OG material layer. Then, the heat treatment is performed in a nitrogen atmosphere at 95-1.
It is preferable to bake in the range of 00 ° C. for 2 minutes to form an SOG material layer.

[0008]

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples.

Example 1 In this example, an application example to a so-called LSI manufacturing process will be described. (CH ₃ ) ₂ Si (OH) as an adhesion enhancing material on a silicon wafer substrate which is the substrate to be processed
_The SOG material represented by ₂ is coated and applied so as to have a thickness of 0.05 μm, and baked at 100 ° C. for 2 minutes on a hot plate in a nitrogen atmosphere to form an SOG material layer. 1.0 μ of SAL601 manufactured by Shipley Co., Ltd., which is a commercial type chemically amplified negative resist containing OH group in
It was coated and applied so as to have a film thickness of m, and baked at 125 ° C. for 2 minutes on a hot plate in a nitrogen atmosphere. Next, after irradiating the resist material layer with a high energy X-ray to a desired region with a dose of 100 to 400 mJ / cm ² , post exposure bake is performed at 105 ° C. on a hot plate in a nitrogen atmosphere. Processing for 1 minute, followed by development with a 0.27N tetramethylammonium hydroxide (hereinafter abbreviated as TMAH) solution for 5 minutes, and then rinsed with pure water for 1 minute. Then, a desired resist pattern was obtained by finally performing a drying process. In the HMDS that has been used as an adhesion enhancing material, the minimum resolution pattern dimension was 0.2 μm and the maximum A was 5 when the resist material layer thickness was 1.0 μm. The minimum resolution pattern size is 0.18 μm and maximum A is
Was 5.6, and the resolution and the maximum A were improved. The main reason for these improvements is that when the SOG material layer is used as the adhesion enhancing material, the work substrate and the resist pattern are more firmly adhered to each other than when HMDS is used. This is because it has decreased.

Regarding the factor of the improvement in the resolution, FIG.
This will be described with reference to FIG. In FIGS. 1 and 2, reference numeral 1 is a substrate to be processed, 2 is an SOG material layer, and 3 is a resist material layer. A natural oxide film of Si is formed on the surface of silicon (hereinafter abbreviated as Si) which is the object substrate 1 to be processed in FIG. 1, and further, the object substrate 1 to be processed in FIG.
Si-OH is formed on the outermost surface layer. When the SOG material layer 2 whose main component is (CH ₃ ) ₂ Si (OH) ₂ is coated on the surface of the substrate to be processed as an adhesion enhancing material and a heat treatment is performed, a dehydration condensation reaction occurs, and the object to be processed in FIG. Siloxane bond (Si-OS) between the substrate 1 and the SOG material layer 2
It is presumed that i) is formed and firmly adheres. FIG.
As described above, the SOG material layer is dehydrated and condensed by heating to generate water. Therefore, if the amount of water generated can be measured, the degree of dehydration condensation can be known, and the amount of OH groups remaining in the SOG material layer can be estimated.

FIG. 3 is a graph showing the results of examining the temperature programmed desorption of water in the SOG material layer. In FIG. 3, the vertical axis represents the normalized ionic strength of water and the horizontal axis represents the temperature (° C.). The measurement was performed by putting a Si substrate coated with the SOG material layer in a closed container, heating the temperature, and measuring the generated water with an ionization mass spectrometer. From Figure 3, SOG material layer is 100 ℃
Desorption of water begins more rapidly. It is presumed that this is due to dehydration condensation, adsorbed water on the surface of the SOG material layer, and water contained in the material layer. Desorption and adsorption of water are in equilibrium at around 150 ° C, and water is desorbed when the temperature is further raised to 150 ° C or higher. It is presumed that this is because dehydration condensation becomes dominant in water desorption at 150 ° C or higher. That is, the SOG of FIG.
In this embodiment, the baking after coating the material layer 2 was 100 ° C. for 2 minutes, but if the baking is performed at a temperature higher than this, the dehydration condensation reaction in the SOG material layer 2 in FIG. The OH groups in the SOG material layer 2 decreased, and the adhesiveness decreased. On the surface of the SOG material layer 2, there are OH groups that have not caused the dehydration condensation reaction. Si-OH in Figure 2
Indicates that Si—OH groups are present in the surface layer of the SOG material layer. A commercially available resist SAL601 containing an OH group on the SOG material layer 2 of FIG. 2 (P represents a resist of a monomer unit, and P-OH indicates that the OH group is contained in the resist). When the layer 3 is applied / covered and baked at 125 ° C. for 2 minutes, a dehydration condensation reaction proceeds between the SOG material layer 2 of FIG. 2 and the resist material layer 3 of FIG. It is estimated that the In the case of this embodiment, the baking temperature is set to 100.
Although the temperature was 2 ° C. for 2 minutes, almost the same result was obtained even when the baking temperature was 95 to 105 ° C. As described above, in the present invention, the substrate to be processed and the SOG material layer and the SOG material layer and the resist material layer are strongly chemically bonded to each other by the dehydration condensation reaction, so that the adhesion is improved and the resolution is improved. That is clear.

Example 2 In this example, an application example to a so-called micromachine process will be described. A copper film as a conductive material layer was vapor-deposited and coated on the Si substrate by a sputtering method so as to have a thickness of 0.1 μm. The SOG material represented by (CH ₃ ) ₂ Si (OH) _{2 as} the main component of the adhesion enhancing material is coated and applied on the copper film to a thickness of 0.05 μm,
Baking was performed at 100 ° C. for 2 minutes on a hot plate in a nitrogen atmosphere. As the resist material layer, a positive resist material polymethylmethacrylate (hereinafter abbreviated as PMMA) was formed into a film having a thickness of 100 μm by a casting method. The PMMA film was immersed in a sulfuric acid solution for 30 minutes.
The sulfuric acid solution-treated resist material layer was placed on the SOG material layer and heat-treated on a hot plate in a nitrogen atmosphere at 200 ° C. for 30 minutes. Next, the high-energy X-rays are applied to the resist material layer in a desired region of 400 to 400
Irradiation was performed at a dose of 1000 mJ / cm ² . Next, using methyl isobutyl ketone (MiBK) as a developing solution,
0 minute development process, isopropyl alcohol (IPA)
A desired resist pattern was obtained by performing a rinsing process using the above, and finally performing a drying process. Next, the SOG material layer in the non-patterned region was removed by reactive ion etching to expose the copper conductive material layer under the SOG material layer. Then, copper electroplating was performed with a copper sulfate plating solution using the resist pattern as a template mask to obtain a desired copper pattern in a non-patterned region with a thickness of 90 μm. When the resist material layer is formed on the conventional HMDS material layer or the SOG material layer baked at more than 200 ° C., the copper sulfate plating solution forms the resist pattern and the SOG material layer, or the SOG material layer and the conductive material layer. The resist pattern was peeled off and collapsed.
When the OG material layer is used as an adhesion enhancing material, since it has a strong adhesion, there is no phenomenon of peeling or falling of the pattern, and the phenomenon that the copper plating solution penetrates into the area, and the micromachine manufacturing process. Performance and yield have improved. For example, copper plating film thickness 90μm and size 5
The yield of the rectangular pattern of × 30 μm was about 60% in the conventional method and 95% or more in the method of the present invention.

Factors for improving the performance and yield in the micromachine process will be described with reference to FIGS. In FIGS. 4 and 5, reference numeral 1 denotes a substrate to be processed, 4 a conductive material layer of copper, 5 an SOG material layer, and 6 a resist material layer. A copper film as the conductive material layer 4 of FIG. 4 was vapor-deposited and coated on the Si substrate, which is the substrate 1 to be processed of FIG. 4, by the sputtering method so as to have a thickness of 0.1 μm. A natural oxide film of copper is formed on the surface of the conductive material layer 4 in FIG. 4, and further Cu—OH is formed under the influence of moisture in the air. On the surface of the substrate to be processed, (CH ₃ ) ₂ Si (O
H) ₂ is applied to the SOG material layer 5 shown in FIG. 4 as an adhesion enhancer so as to have a thickness of 0.05 μm, and heat treatment causes a dehydration condensation reaction, so that the conductive material layer 4 shown in FIG. It is presumed that a siloxane bond (Si-O-Si) is formed in the SOG material layer 5 of No. 4 and the SOG material layer 5 of FIG. On the surface of the SOG material layer 5 in FIG. 5, there are OH groups that have not caused the dehydration condensation reaction. The resist material layer of PMMA formed by the casting method does not contain OH groups in the resist material layer. However, the treatment with sulfuric acid causes dehydration and decomposition on the surface of the resist material layer to form OH groups.
The same effect is obtained as when a resist material layer containing an H group is used. Next, the PMMA resist material layer 6 of FIG. 5 which was formed by the casting method and treated with sulfuric acid was placed on the SOG material layer 5 of FIG. 5 and was baked at 200 ° C. for 30 minutes to cause a dehydration condensation reaction and firmly adhered. . The baking after coating the SOG material layer 5 in FIG.
Although the baking was performed at 2 ° C. for 2 minutes, when the baking was performed at a temperature exceeding 100 ° C. and a time exceeding 2 minutes, the dehydration condensation reaction in the SOG material layer proceeded excessively and the OH groups decreased, and
The amount of dehydration condensation reaction between the material layer 5 and the resist material layer 6 of FIG. 5 was reduced, and the adhesion was lowered. As described above, in the present invention, the substrate to be processed and the SOG material layer and the SOG material layer and the resist material layer are strongly chemically bonded to each other by the dehydration condensation reaction, so that the adhesion is improved and the resolution is improved. That is clear.

Example 3 A copper film was deposited and coated as a conductive material layer on a Si wafer substrate by a sputtering method so as to have a thickness of 0.1 μm to obtain a substrate to be processed. An SOG material layer was coated and applied as an adhesion enhancing material on the copper film. The resist material layer is P
The MMA resist solution was made to contain a polymerization initiator, 2,2-azobisisobutyronitrile (hereinafter abbreviated as AIBN), to obtain a resist material layer having a thickness of 100 μm by a casting method. This resist material layer is the AIBN in the resist.
Caused the PMMA to thermally crosslink during casting. Below, a copper conductive pattern was obtained by the micromachine manufacturing process under the same method and conditions as in Example 2. SOG of the present invention
When the material layer is used as an adhesion enhancing material, since it has strong adhesion, peeling and collapse phenomenon of the pattern, and the phenomenon that the copper plating solution penetrates into the interface between the resist pattern and the conductive material layer, There was none. The main reason for obtaining the copper pattern having such a resolution is that the substrate to be processed and the SO
This is because the G material layer, the SOG material layer, and the resist material layer are firmly adhered to each other. That is, it is obvious that the resolution was improved by using the SOG material layer of the present invention as the adhesion enhancing material.

[0015]

According to the adhesion enhancing pattern forming method of the present invention, the surface of the substrate to be processed is coated with the SOG material layer as an adhesion enhancing material before the resist material layer is coated onto the substrate to be processed. Of the SOG material layer and the SOG material layer are improved, and at the same time, the adhesion between the SOG material layer and the resist material layer is improved. By this method, LS
(1) Forming a pattern having a large aspect ratio in the manufacturing process and the micromachine manufacturing process, and preventing the plating solution from entering the interface between the substrate to be processed and the resist pattern in the electroplating process of the micromachine manufacturing process. With characteristics. The SOG material layer is LSI
It is widely used as an interlayer insulating film, a passivation film, a step covering film, etc. in the manufacturing process. However,
In these applications, the heat treatment after coating is carried out at a high temperature above 200 ° C. This is because the organic component in the SOG film is removed by the high temperature heat treatment, and the SOG film is used after being transformed into inorganic SiO ₂ . In the present invention, the heat treatment after coating is 100
Since it is carried out at a low temperature of about C, inorganic SiO ₂ is hardly formed. That is, the SOG used in the present invention and the SOG generally used are completely different in the form after the film formation.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing the principle of the present invention when applied to an LSI process.

FIG. 2 is an explanatory diagram showing the principle of the present invention when applied to an LSI process.

FIG. 3 is a graph showing the results of thermal desorption analysis of water in the SOG material layer.

FIG. 4 is an explanatory diagram showing the principle of the present invention when applied to a micromachine process.

FIG. 5 is an explanatory diagram showing the principle of the present invention when applied to a micromachine process.

[Explanation of symbols]

1: substrate to be processed, 2: SOG material layer, 3: resist material layer, 4: copper conductive material layer, 5: SOG material layer, 6:
Resist material layer

Claims (5)

[Claims] 1. In a pattern forming method for obtaining a desired pattern with a substrate to be processed, an adhesion enhancing material layer, and a resist material layer, the adhesion enhancing material layer is represented by the general formula: R _n S
i (OH) _4-n (wherein R is at least one group selected from the group consisting of a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, and a cyclic saturated hydrocarbon group, n is 1, A few
Represented by any of the above), a spin-on-glass material layer containing at least one silanol group (Si—OH) is used. 2. The pattern forming method according to claim 1, wherein a resist material layer containing an OH group in the resist material layer or on the surface of the resist material layer is used as the resist material layer. 3. As the resist material layer, a resist material layer containing an OH group in the resist material layer or on the surface of the resist material layer and the adhesion enhancing material layer have the general formula:
R _n Si (OH) _4-n (wherein R is at least one group selected from the group consisting of a saturated aliphatic hydrocarbon group, an unsaturated aliphatic hydrocarbon group, and a cyclic saturated hydrocarbon group, n is The method for forming a pattern according to claim 1, which is combined with a spin-on-glass material layer containing at least one silanol group (Si—OH) represented by any one of 1, 2, and 3). 4. The pattern forming method according to claim 1, further comprising a heat treatment step after coating the spin-on-glass material layer. 5. The pattern forming method according to claim 1, wherein the heat treatment after coating the spin-on-glass material layer is a treatment of baking in a nitrogen atmosphere at 95 to 105 ° C. for 2 minutes to form a spin-on-glass material layer. .