JPH04130324A - Positive type resist composition - Google Patents

Abstract

PURPOSE:To obtain the positive type resist which has high oxygen plasma resistance and has the excellent sectional shape of patterns by using the alkaline-soluble ladder silicone polymer expressed by specific formula and photosensitive 1, 2-naphthoquinone diazie group-contg. compd. as essential components. CONSTITUTION:The alkaline-soluble ladder silicone polymer expressed by the formula is used as the alkaline-soluble resin and n and m in the formula are selected at 0.5<=n/(n+m)<=0.7. The 1, 2-naphthoquinone diazie group-contg. compd. is preferable as the photosensitive compd. The compounding ratio of the alkaline-soluble ladder silicone polymer and the photosensitive compd. is selected at <=100 pts. wt., more preferably <=55 pts. wt. per 10 pts. wt. photosensitive compd. The positive type resist compsn. having the good characteristics is obtd. by this constitution.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a novel positive resist composition, more specifically, a novel positive resist composition which has high resistance to oxygen plasma and which is suitable for manufacturing semiconductor devices and electronic components, and which has a flat cross-sectional shape. The present invention relates to a positive resist composition having excellent properties.

Conventional technology In recent years, in the semiconductor industry, industrial computers,
The demand for office automation, personal computers, etc. is expanding dramatically, and the technology continues to develop rapidly. Along with this, semiconductor integrated circuit devices are also rapidly becoming denser and more highly integrated. Many proposals and innovations have been made regarding the manufacturing process. For example, in the manufacturing of semiconductor integrated circuit devices, pattern formation on the submicron order is required, and for this purpose, the resists used in the phosphorography process are also high-resolution, replacing the negative resists that have been the mainstream. Positive resists are becoming mainstream. Furthermore, in the pattern forming method using this positive resist,
Multilayer resist methods with high dimensional accuracy are increasingly being used.

In particular, the surface of a board with multilayered circuits performed by multiple phosphorography processes to obtain a high degree of integration has an uneven surface. The resist method has become an essential pattern forming method.

This multilayer resist method is a method in which a positive resist layer is provided as the top layer, this is patterned, and then the pattern is sequentially transferred to the lower layer by dry etching to form a pattern with high dimensional accuracy on the substrate. Moreover, by using a reactive ion etching method with high anisotropy in the dry etching, a product with higher dimensional accuracy can be obtained.

Regarding such multilayer resist methods, two-layer resist structure and three-layer resist structure are known.
Generally, the former consists of a positive resist layer (upper layer) and an organic film layer (lower layer), and the latter has a metal thin film layer (intermediate layer) between the upper and lower layers of a two-layer resist structure. In this multilayer resist method, whether it is a two-layer resist structure or a three-layer resist structure, it has the same effect in that it can form patterns with high dimensional accuracy, but considering the work process. Naturally, a two-layer resist structure is preferable.

However, in this two-layer resist structure, the organic film layer is formed on the substrate for the purpose of flattening the surface of the substrate, which usually has an uneven surface, and the positive resist layer is formed directly on top of the organic film layer, which does not change in quality at the contact surface between them. In addition, the positive resist that serves as the upper layer is required to be resistant to oxygen plasma and capable of forming a pattern with an excellent cross-sectional shape. As described above, a pattern with excellent oxygen plasma resistance and cross-sectional shape is required for a positive resist when the underlying organic film layer is etched by a dry etching method using oxygen gas. This is because the pattern formed must have the function of a mask.

However, conventional positive resists generally do not have sufficient resistance to oxygen plasma, and when the underlying organic film layer is dry-etched, the resist that serves as a mask is also thinned at the same time. In pattern formation, there is a problem in that the resist serving as a mask disappears before etching of the organic film layer is completed.

Therefore, in order to respond to the recent trend toward finer patterns, we have developed a three-layer resist structure with a complicated work process in which a metal thin film layer is provided as an intermediate layer and this metal thin film layer is used as a mask. The current situation is that it must be used.

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 the three-layer resist structure, so it has extremely high future prospects. If a positive resist with high oxygen plasma resistance is developed, the above problem can be solved. Therefore, in the semiconductor industry, there is a need to develop a positive resist with high oxygen plasma resistance that can be used in this two-layer resist structure. has become an important issue.

On the other hand, regarding the development of such a positive resist with high oxygen plasma resistance, when etching an organic film used as a layer to be etched, for example, in recent years, heat resistance and chemical It has been strongly desired because it is useful as a mask material when etching imide-based resins, which are now widely used as protective films and interlayer insulating films due to their physical stability.

Problems to be Solved by the Invention Under these circumstances, the present invention provides a positive resist composition that has high resistance to oxygen plasma and is suitable for manufacturing semiconductor elements and electronic components, and has an excellent pattern cross-sectional shape. It was done for the purpose of

Means for Solving the Problems As a result of intensive research to develop a positive resist composition having the above-mentioned preferable properties, the inventors of the present invention discovered that a specific alkali-soluble ladder silicone polymer was used as the alkali-soluble resin. The inventors discovered that the object could be achieved by using a composition that had previously been used, and based on this knowledge, the present invention was completed.

That is, the present invention provides a positive resist composition containing an alkali-soluble resin and a photosensitive compound as main components, in which the alkali-soluble resin has the general formula The present invention provides a positive resist composition characterized by being an alkali-soluble ladder silicone polymer represented by the following formula.

The present invention will be explained in detail below.

In the composition of the present invention, as the alkali-soluble resin,
An alkali-soluble ladder silicone polymer represented by the general formula % (in which n and m have the same meanings as above) is used. This ladder silicone skeleton has oxygen plasma resistance, is alkali soluble, has a main chain closest to the structure of silicon oxide, and has seven side chains.
It is a polymer with enolic hydroxyl groups.

n and m in the general formula (I) have the formula 0.5≦
It is necessary to satisfy the relationship ≦0.7 n0m, nA. If the value of □ deviates from the above range, the object of the present invention cannot be fully achieved.

The alkali-soluble ladder silicone polymer is soluble in alkaline solvents, but it is also easily soluble in organic solvents such as alcohol, ether, amide, ketone, ester, and cellosolve. A film can be formed by dissolving it in a solvent.

The photosensitive compound in the composition of the present invention includes 1.2-
Compounds containing naphthoquinonediazide groups are preferably used.

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

Examples of compounds having a phenolic hydroxyl group or amino group include 2.3.4-trihydroxybenzophenone, 2.2', 4.4'-tetrahydroxybenzophenone, 2,3.4.4'-tetrahydroxybenzophenone, etc. polyhydroxybenzophenone, or alkino gallate, aryl gallate, phenol, p-
Methoxyphenonohedimethylphenol, hydroquinone, bisphenol A1 naphthol, pyrocatechol,
Examples include pyrogallol, pyrogallol monomethyl ether, pyrogallol-1,3-dimethyl ether, gallic acid, gallic acid esterified or etherified with some hydroxyl groups left, aniline, and p-aminodiphenylamine.

Regarding the blending ratio of the alkali-soluble ladder silicone polymer represented by the general formula (1) and the photosensitive compound, the amount of the alkali-soluble ladder silicone polymer is 100 parts by weight or less, preferably 5 parts by weight, per 10 parts by weight of the photosensitive compound.
It is used in a proportion that is 5 parts by weight or less. If the amount of the alkali-soluble ladder silicone polymer used exceeds 100 parts by weight, the mask pattern fidelity of the resulting image will be poor and the transferability will be reduced.

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 solvents include ketones such as acetone, methyl ethyl ketone, cyclohexanone, isoamyl ketone; monomethyl ether, monoethyl ether, monopropyl ether of ethylene glycol, engineered ethylene glycol heptanoacetate, diethylene glycol or 1t diethylene glycol heptanoacetate. , polyhydric alcohols and their derivatives such as monobutyl ether or monophenyl ether; cyclic ethers such as dioxane;
Examples include esters such as methyl lactate, ethyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl pyruvate, and ethyl pyruvate. These may be used alone or in combination of two or more.

The positive resist compositions of the present invention may further contain compatible additives such as sensitizers, additional resins, plasticizers, stabilizers, or colorants to make the developed image more visible. It is possible to add and contain commonly used materials.

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

One example of a preferred method of using the composition of the present invention is as follows:
First, a solution of the composition is applied onto the object to be etched using a spinner, and after drying, the quinonediazide group-containing compound is exposed to active light suitable for solubilization, such as a low-pressure mercury lamp, a high-pressure mercury lamp, or an ultra-high-pressure mercury lamp. , actinic rays and excimer lasers using arc lamps, xenon lamps, etc. as light sources,
Irradiation is performed selectively through a desired mask or by reduction projection exposure. Next, the portion solubilized by exposure is dissolved and removed using a developer, for example, an alkaline aqueous solution such as a 1 to 2% by weight aqueous sodium hydroxide solution, an aqueous tetramethylammonium hydroxide solution, and an aqueous trimethyl(2-hydroquinethyl)ammonium hydroxide solution. In this way, a resist pattern is formed on the object to be etched. Next, a pattern faithful to the mask pattern can be obtained by etching the exposed object to be etched by dry etching using oxygen gas, such as plasma etching or reactive on etching.

Effects of the Invention By using a specific alkali-soluble ladder silicone polymer, the positive resist composition of the present invention has higher resistance to oxygen plasma than conventional ones, so it can be used as a mask for dry etching using oxygen gas. By using it as the upper layer of a multilayer resist method using a two-layer resist structure, which is particularly effective for obtaining patterns with high dimensional accuracy, it is easy to form fine patterns on the submicron order. It can be used as a mask material for almost all organic films such as resin films.

In addition, by introducing a substituent having a phenolic hydroxyl group into the side chain of the alkali-soluble ladder silicone polymer at an appropriate ratio, the solubility in aqueous alkaline solutions can be controlled, and it is widely used, especially as a developer for positive resists. This improves the developability for the tetramethylammonium hydroxide aqueous solution that is currently used, and as a result, the resolution can be significantly improved.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

Production Example 1 In a 500 m 12 three-necked flask equipped with a stirrer, reflux condenser, dropping funnel, and thermometer, 88% of sodium hydrogen carbonate was added.
After adding 4.0y (1.0mol) and 400ml (l) of water, from the dropping funnel, add 51.1g (0.20mol) of p-methoxybenzyltrichlorosilane, 1g (0.10mol) of phenyltrichlororane, and 100mQ of diethyl ether. was added dropwise over 2 hours and further aged for 1 hour.After the reaction was completed, the reaction mixture was extracted with ether and the ether was distilled off under reduced pressure. wt% solution 0.
2 g was added and heated at 200°C for 2 hours to obtain copoly(p-methoxybenzylsilsesquioxane phenylrunsesquioxane).

The obtained polymer was dissolved in 150+++ (2) acetonitrile, and 80 g of trimethylsilyl iodide (0,
After cooling, free iodine was reduced with an aqueous solution of sodium hydrogen sulfate, and the organic layer was dissolved. The target alkali-soluble ladder silicone polymer, poly(p-hydroxy 29.1 g of benzylsilsesquioxane (phenylsilsesquioxane) was obtained.The NMR spectrum and IR spectrum of this product are shown below.

NMR spectrum (60 MHz DMSO-d6) H H H H IR spectrum (νcm-') 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, 2 moles of naphthoquinonediazide-5-sulfonic acid, and 1 mol of 2.3.4-trihydroxybenzphenone. After dissolving 25 parts by weight of ester [i] in 300 parts by weight of ethylene glycol monoethyl ether acetate, it was filtered through a membrane filter with 0.2 μm pores.
A coating solution of a positive resist composition was prepared.

Next, this coating solution was applied uniformly to a film thickness of 1.3 μm on a 3-inch silicon wafer using a TR-4000 type resist coater (manufactured by Tatsumo Co., Ltd.), and heated at 110°C for 90°C.
Dry on a hot plate for seconds. Next, ultraviolet rays were irradiated through the test chart using a reduction projection exposure device (1505G B A type wafer stepper manufactured by Kon Co., Ltd.), and then irradiated with a 2.38% by weight tetramethylammonium hydroxide aqueous solution at 23°C for 30 seconds. Deep developed. The obtained resist pattern was then processed using an OAPM-400 parallel plate plasma etching device.
(manufactured by Tokyo Ohka Kogyo Co., Ltd.) using pressure Q, Q2 Torr.
, oxygen gas flow rate 20cc/min, PF output 100W,
When reactive ion etching was carried out at a processing temperature of 25°C, the amount of film loss of the resist film decreased by 1 in 5 minutes.
It was 30 nm.

Production Example 2 The amounts of p-methoxybenzyltrichlorosilane and phenyltrichlorosilane in Production Example 1 were each 38.3.
g (0.15 mol) and 42.29 (0.20 mol+
) was replaced with poly(
32.2 g of p-hydroxybenzylsilsesquioxane (phenylsilsesquioxane) was obtained.

Production Example 3 The amounts of p-methoxybenzyltrichlorosilane and phenyltrichlorosilane in Production Example 1 were each 51.1
g (0,20mol) and lo, 5g (0,05mol)
Except for replacing it with f! Poly(p-hydroxybenzylsilsesquioxane phenylsilsesquioxane) 24. by the same operation as Ii. I got h.

Comparative Example 1 Same as Example 1 except that poly(p-hydroxybenzylsilsesquioxane phenylsilsesquioxane) obtained in Production Example 2 was used as the alkali-soluble ladder silicone polymer. It was carried out as follows.

The formed resist pattern did not have a cross-sectional shape with excellent verticality, and was not practical.

Comparative Example 2 Same as Example 1 except that the poly(p-hydroxybenzylsilsesquioxane phenylsilsesquioxane) obtained in Production Example 3 was used as the alkali-soluble ladder silicone polymer. It was carried out as follows.

The formed resist pattern did not have a cross-sectional shape with excellent perpendicularity, and its resolution was also poor, making it impractical.

Claims (1)

[Scope of Claims] 1. In a positive resist composition containing an alkali-soluble resin and a photosensitive compound as main components, the alkali-soluble resin has a general formula ▲a mathematical formula, a chemical formula, a table, etc.▼ (n in the formula and m is a number satisfying the relationship of the formula 0.5≦n/(n+m)≦0.7) A positive resist composition characterized by being an alkali-soluble ladder silicone polymer represented by the following formula. 2. The positive resist composition according to claim 1, wherein the photosensitive compound is a 1,2-naphthoquinonediazide group-containing compound.