JP2567984B2 - Positive resist composition - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel positive resist composition, and more particularly to a resist composition having high resistance to oxygen plasma suitable for the production of semiconductor devices and electronic parts and having a cross-sectional shape of a pattern. The present invention relates to a positive resist composition having excellent properties.

2. Description of the Related Art In recent years, in the semiconductor industry, the demand for industrial computers, office automation, personal computers, etc. has expanded dramatically, and the technology has continued to develop rapidly. As a result of rapid increase in density and integration, many proposals and ingenuities have been made regarding the manufacturing process. For example, in the manufacture of semiconductor integrated circuit elements, pattern formation on the order of submicrons is required. Therefore, for the resist used in the lithography process,
Positive resists with high resolution are becoming mainstream instead of negative resists that have been mainstream until now. further,
Also in the pattern forming method using this positive type resist, a multi-layer resist method with high dimensional accuracy is often used. In particular, in a substrate in which circuits are multilayered by performing a plurality of lithography steps in order to obtain a high degree of integration, the surface has unevenness, and the multilayer resist is applied to a substrate having such an uneven surface. The method is an essential pattern forming method.

This multilayer resist method is a method of forming a positive resist layer on the uppermost layer, patterning this, and then sequentially transferring the pattern to a lower layer by a dry etching method to form a pattern with high dimensional accuracy on a substrate. By using the reactive ion etching method having a high anisotropy also in the dry etching, it is possible to obtain the one with higher dimensional accuracy.

Regarding such a multi-layer resist method, a two-layer resist structure and a three-layer resist structure are known, and the former is generally composed of a positive resist layer (upper layer) and an organic film layer (lower layer), The latter has a metal thin film layer (intermediate layer) between the upper layer and the lower layer of the two-layer resist structure. In this multi-layer resist method, whichever of two-layer resist structure or three-layer resist structure,
Although it has the same effect in that a pattern with high dimensional accuracy can be formed, a two-layer resist structure is naturally preferable in consideration of the working process.

However, in this two-layer resist structure, the organic film layer formed on the substrate for the purpose of flattening the surface of the substrate which normally has the uneven surface and the positive resist directly provided thereon are altered in their contact surfaces. In particular, the positive resist which is the upper layer is required to have oxygen plasma resistance and capable of forming a pattern having an excellent cross-sectional shape. As described above, the positive resist is required to have a pattern excellent in oxygen plasma resistance and cross-sectional shape, when the lower organic film layer is etched by a dry etching method using oxygen gas, the positive resist is required. This is because the pattern formed by must have a function as a mask.

However, conventional positive type resists generally do not have sufficient resistance to oxygen plasma, and when the lower organic film layer is dry-etched, the resist film to be used as this mask is also thinned. In the pattern formation, there is a problem that the resist as a mask disappears before the etching of the organic film layer is completed.

Therefore, in order to cope with the recent tendency of pattern miniaturization, it is necessary to provide a metal thin film layer as an intermediate layer and use a three-layer resist structure having a complicated working process using the metal thin film layer as a mask. That is the current situation.

On the other hand, the two-layer resist structure is effective as a pattern forming method with high dimensional accuracy, and the work process is easier than that of the three-layer resist structure.
If a positive resist having extremely high future resistance and high oxygen plasma resistance is developed, the above problems can be solved. Therefore, in the semiconductor industry, oxygen plasma resistance which can be used for this two-layer resist structure is improved. The development of high positive resist has become an important issue.

On the other hand, regarding the development of such a positive resist having high oxygen plasma resistance, when etching the organic film used as the etching target layer, for example, in recent years, in the production of semiconductor elements and electronic parts, heat resistance and chemical resistance It has been strongly desired because it is useful as a mask material for etching an imide resin, which has been widely used as a protective film or an interlayer insulating film due to advantages such as physical stability.

SUMMARY OF THE INVENTION Under the circumstances, the present invention has high resistance to oxygen plasma suitable for manufacturing semiconductor elements and electronic components,
In addition, the object is to provide a positive resist composition having an excellent cross-sectional shape of the pattern.

Means for Solving the Problems As a result of intensive studies to develop a positive resist composition having the above-mentioned preferable properties, the present inventors have used a specific alkali-soluble ladder silicone polymer as an alkali-soluble resin. It was found that the above composition could achieve the object, and based on this finding, the present invention was completed.

That is, the present invention is a positive resist composition containing an alkali-soluble resin and a photosensitive compound as main components,
The alkali-soluble resin has the general formula (Where n and m are the formulas The present invention provides a positive resist composition, which is an alkali-soluble ladder silicone polymer represented by the formula (1).

 Hereinafter, the present invention will be described in detail.

In the composition of the present invention, as the alkali-soluble resin, An alkali-soluble ladder silicone polymer represented by the formula (n and m have the same meaning as described above) is used. This ladder silicone polymer is a polymer having oxygen plasma resistance, alkali solubility, and a ladder silicone skeleton whose main chain is closest to the structure of silicon oxide and which has a phenolic hydroxyl group on its side chain. .

N and m in the general formula (I) are represented by the formula However, if the value of n / n + m deviates from the above range, the object of the present invention cannot be sufficiently achieved.

The alkali-soluble ladder silicone polymer is soluble in an alkaline solvent, but since it is easily dissolved in an organic solvent such as an alcohol-based, ether-based, amide-based, ketone-based, ester-based or cellosolve-based polymer, these It can be dissolved in a solvent to form a film.

The photosensitive compound in the composition of the present invention includes 1,2-
A naphthoquinonediazide group-containing compound is preferably used.

Examples of such a compound include those obtained by partially or completely esterifying or partially or completely amidating a sulfonic acid of 1,2-naphthoquinonediazide and a compound having a phenolic hydroxyl group or an amino group.

Examples of the compound having a phenolic hydroxyl group or an amino group include 2,3,4-trihydroxybenzophenone,
2,2 ', 4,4'-tetrahydroxybenzophenone, 2,3,
Polyhydroxybenzophenone such as 4,4′-tetrahydroxybenzophenone, or alkyl gallate,
Aryl gallate, phenol, p-methoxyphenol, dimethylphenol, hydroquinone, bisphenol A, naphthol, pyrocatechol, pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-
Examples thereof include dimethyl ether, gallic acid, gallic acid esterified or etherified with some hydroxyl groups left, aniline, and p-aminodiphenylamine.

Regarding the mixing ratio of the alkali-soluble ladder silicone polymer represented by the general formula (I) and the photosensitive compound, the alkali-soluble ladder silicone polymer is 100 parts by weight or less, preferably 55 parts by weight, relative to 10 parts by weight of the photosensitive compound. It is used in a proportion such that it is less than or equal to parts by weight. If the amount of the alkali-soluble ladder silicone polymer used exceeds 100 parts by weight, the fidelity of the mask pattern of the obtained image will be poor and the transferability will be poor.

The composition of the present invention is advantageously used in the form of a solution by dissolving the alkali-soluble ladder silicone polymer represented by the general formula (I) and the photosensitive compound in a suitable solvent.

Examples of such a solvent include ketones such as acetone, methyl ethyl ketone, cyclohexanone and methyl isoamyl ketone; ethylene glycol, ethylene glycol monoacetate, diethylene glycol or diethylene glycol monoacetate monomethyl ether,
Polyhydric alcohols such as monoethyl ether, monopropyl ether, monobutyl ether or monophenyl ether and derivatives thereof; cyclic ethers such as dioxane; methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, pyruvic acid Examples thereof include esters such as methyl and ethyl pyruvate. These may be used alone or in combination of two or more.

In the positive resist composition of the present invention, further compatible additives such as a sensitizer, an additional resin, a plasticizer, a stabilizer or a colorant for making the developed image more visible. The conventional one can be added and contained.

The material to be etched that is etched by performing the dry etching treatment using the composition of the present invention as a mask is not particularly limited as long as it can be dry-etched by oxygen plasma, and almost any organic material can be used. Specific examples include organic photoresists, polymethyl methacrylate, copolymers of methyl methacrylate and methacrylic acid, and imide resins used as the lower layer of a two-layer resist structure.

To give an example of the preferred use of the composition of the present invention, first, a solution of the composition is applied onto an object to be etched by a spinner or the like, and after drying, the quinonediazide group-containing compound is exposed to light and solubilized. A suitable actinic ray, for example, a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, an arc lamp, or an xenon lamp is used as a light source, or an excimer laser is selectively irradiated through a desired mask or a reduced projection exposure method. Irradiation. Then a developer, eg 1-
By dissolving and removing the portion solubilized by exposure with an alkaline aqueous solution such as a 2% by weight aqueous sodium hydroxide solution, an aqueous tetramethylammonium hydroxide solution, or an aqueous trimethyl (2-hydroxyethyl) ammonium hydroxide solution, the material to be etched is removed. A resist pattern is formed. Next, the exposed object to be etched is dry-etched by oxygen gas, for example, a plasma etching method,
By etching by the reactive ion etching method or the like, a pattern faithful to the mask pattern can be obtained.

EFFECTS OF THE INVENTION The positive resist composition of the present invention has a higher resistance to oxygen plasma than conventional ones by using a specific alkali-soluble ladder silicone polymer, and therefore a mask for dry etching using oxygen gas. It is extremely useful as an upper layer of a multi-layer resist method having a two-layer resist structure which is particularly effective for obtaining a pattern with high dimensional accuracy, and it is easy to form a submicron-order fine pattern. It can be used as a mask material for almost all organic films such as a resin film.

In addition, by introducing a substituent having a phenolic hydroxyl group into the side chain of the alkali-soluble ladder silicone polymer in an appropriate ratio, the solubility in an alkaline aqueous solution is controlled, and it is widely used especially as a developer for positive resist. It is possible to improve the developability with respect to the existing tetramethylammonium hydroxide aqueous solution, and as a result, to significantly improve the resolution.

EXAMPLES Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

Production Example 1 84.0 g of sodium hydrogen carbonate was added to a 500 ml three-necked flask equipped with a reflux condenser, a dropping funnel and a thermometer.
(1.0 mol) and 400 ml of water were added, and then 51.1 g (0.2 mol) of p-methoxybenzyltrichlorosilane was added from a dropping funnel.
0 mol), 21.1 g (0.10 mol) of benzyltrichlorosilane and 100 ml of diethyl ether were added dropwise over 2 hours,
It was further aged for 1 hour. After completion of the reaction, the reaction mixture was extracted with ether, and the ether was distilled off under reduced pressure, and then 0.2 g of a 10 wt% solution of potassium hydroxide was added to the obtained hydrolysis product.
Is added and heated at 200 ° C. for 2 hours to produce copoly (p
-Methoxybenzylsilsesquioxane) was obtained.

The obtained polymer was dissolved in 150 ml of acetonitrile, 80 g (0.40 mol) of trimethylsilyliodide was added thereto, and the mixture was stirred under reflux for 24 hours, then 50 ml of water was added, and further stirred under reflux for 12 hours. After cooling, free iodine is reduced with an aqueous sodium hydrogen sulfite solution, the organic layer is separated, the solvent is distilled off under reduced pressure, and the obtained polymer is reprecipitated with acetone and n-hexane and dried under reduced pressure. As a result, 29.1 g of poly (p-hydroxybenzylsilsesquioxane benzylsilsesquioxane), which is the desired alkali-soluble ladder silicone polymer, was obtained.
The NMR spectrum and IR spectrum of this product are shown below.

NMR spectrum (60MHz DMSO-d ₆₎ IR spectrum (νcm ^-1 ) 3400,1620,1520,1450,1260,1180,1140,1050,840,800 Example 1 75 parts by weight of the alkali-soluble ladder silicone polymer obtained in Production Example 1 and naphthoquinonediazide-5-sulfone 2 mol acid and 2,3,4-trihydroxybenzofenone 1
After dissolving 25 parts by weight of an ester condensate with moles in 300 parts by weight of ethylene glycol monoethyl ether acetate, it was filtered using a membrane filter having 0.2 μm pores to prepare a coating solution of a positive resist composition.

Next, this coating solution was applied onto a 3-inch silicon wafer using a TR-4000 type resist coater (manufactured by Tatsumo Co.) 1.
It was evenly applied to a film thickness of 3 μm and dried at 110 ° C. for 90 seconds on a hot plate. Next reduction projection exposure system 1505G3A
After irradiating ultraviolet rays through a test chart using a mold type wafer stepper (manufactured by Nikon Corporation), a 23% aqueous solution of tetramethylammonium hydroxide
Dip development was performed for 30 seconds at ℃. Then, the obtained resist pattern is used as an OA which is a parallel plate type plasma etching apparatus.
Pressure 0.02 Tor using PM-400 (manufactured by Tokyo Ohka Kogyo Co., Ltd.)
r, oxygen gas flow rate 20cc / min, RF output 100W, processing temperature 25 ℃
When reactive ion etching was performed under these conditions, the amount of film slippage of the resist film was 130 nm in 5 minutes.

Production Example 2 The respective amounts of p-methoxybenzyltrichlorosilane and benzyltrichlorosilane in Production Example 1 were 38.3 g.
(P-Hydroxybenzylsilsesquioxane benzylsilsesquioxane) 32.2 by the same operation as in Preparation Example 1 except that (0.15 mol) and 42.2 g (0.20 mol) were used.
got g.

Production Example 3 The amounts of p-methoxybenzyltrichlorosilane and benzyltrichlorosilane in Production Example 1 were 51.1 g each.
(0.20 mol) and 10.5 g (0.05 mol), except that poly (p-hydroxybenzylsilsesquioxane benzylsilsesquioxane) 24.6 was produced in the same manner as in Production Example 1.
got g.

Comparative Example 1 Similar to Example 1 except that the poly (p-hydroxybenzylsilsesquioxane benzylsilsesquioxane) obtained in Production Example 2 was used as the alkali-soluble ladder silicone polymer. Was carried out.

The formed resist pattern was not a vertical cross-sectional shape and was not practical.

Comparative Example 2 The same as Example 1 except that the poly (p-hydroxybenzylsilsesquioxane benzylsilsesquioxane) obtained in Production Example 3 was used as the alkali-soluble ladder silicone polymer. Was carried out.

The formed resist pattern was not practical because the sectional shape was not excellent in verticality and the resolution was poor.

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Claims (2)

(57) [Claims] 1. A positive resist composition containing an alkali-soluble resin and a photosensitive compound as main components, wherein the alkali-soluble resin is represented by the general formula: (Where n and m are the formulas A positive resist composition, which is an alkali-soluble ladder silicone polymer represented by the formula: 2. The positive resist composition according to claim 1, wherein the photosensitive compound is a 1,2-naphthoquinonediazide group-containing compound.