JPH02189307A - Flattening material - Google Patents

Abstract

PURPOSE:To provide a flattening material excellent in ability to flatten, capable of giving an ideal flat surface irrespective of a difference in level and desirable as an underlayer material in the multilayered resist process, etc., by using a polystyrene (derivative) having a star structure. CONSTITUTION:A flattening material is prepared from a polystyrene (derivative) having a star structure, suitably a polymer having an MW of 500-10000, such as those of formulas I and II. The obtained material is used by dissolving it in a solvent (e.g. toluene), applying the formed solution to, e.g. an insulation film substrate having a difference in level on its surface and causing the obtained organic polymer film to melt and flow by heating it with an infrared lamp or the like to form a flat surface. In order to improve the heat resistance of this film, it is crosslinked by irradiation with ultraviolet rays, etc., and dry- etched to transfer the flat surface onto the insulation film to give a flat insulation film.

Description

[Detailed description of the invention] [Industrial application fields] The present invention relates to a material for planarizing a substrate having irregularities.

[Prior Art] In ultra-small devices such as semiconductor integrated circuit devices or valve memory devices, it is necessary to sequentially laminate insulators and conductor layers.

However, as the number of conductor layers increases to two or three, the height difference between the conductor layers becomes steeper, and disconnections or short circuits occur where the conductor layers intersect, making it difficult to form a substantial laminated structure.

In order to prevent the above-described disconnection of the conductor layer, it is effective to flatten the surface of the insulating layer before forming the conductor layer.

On the other hand, after spin-coating a material with a low heat distortion temperature such as polystyrene with a molecular weight of 100,000 or its derivatives, and then heating it above the heat distortion temperature (e.g. 200°C) to obtain a fluidized and flattened organic resin surface. , a method for obtaining a flat surface of an insulating layer by ultraviolet curing and dry etching (Japanese Unexamined Patent Publication No. 59-225526), and a method for obtaining a flat surface of an insulating layer using polystyrene with a molecular weight of 10,000 or less (Japanese Patent Application Laid-Open No. 150923-1982). There is a public notice).

[Problems to be Solved by the Invention] However, these methods have a problem in that as the step width increases, flattening becomes poorer, and a step with a width of about 500 μm can hardly be flattened.

[Means for Solving the Problem] The present inventors have arrived at the present invention as a result of intensive study on a flattening material that can be almost ideally flattened without dependence on the step width over a step width of 500 μm or more. .

That is, the present invention is a flattening material characterized by being made of polystyrene or a polystyrene derivative having a star-like structure.

As polystyrene or polystyrene derivatives having a star structure, - Shipman: %Formula% [In formula (3), R7, R8 and R8 are a hydrogen atom, a methyl group or a halogen atom, X is a halogen atom, m and n represents O or an integer greater than or equal to 1, and cannot be O at the same time. Examples of the trivalent group of R1 in the general formula (1) include organic polymers represented by 4
Examples include trivalent aromatic groups such as R5, R4, R6 and R6, and phosphorus atoms. Also,
- In Saijin (2), the tetravalent group of R2 is '
/G'% KoC-C) (-, NC) (C)l
C) lBsic) 12CHzSiCH3CH
BSiO3iCHa-Funenin (3), R7, R8
The halogen atom for R9 is preferably a chlorine atom, a bromine atom, or a fluorine atom, and a chlorine atom or a fluorine atom is preferable.

Regarding m and n, preferably nt is 0 to 30,
n is 0-20. m+n is usually 2-30.

The molecular weight (weight average molecular weight) of polystyrene or polystyrene derivative used in the present invention is usually 500 to 10
000, preferably 500 to 1500.

If the molecular weight is less than 500, the organic polymer tends to become a fluid even at room temperature, and the longer the spin rotation time during coating, the thinner the film becomes, causing problems in terms of controllability of the film thickness. Moreover, if the molecular weight exceeds 10,000, it becomes impossible to obtain an ideal flattened surface.

Polystyrene or polystyrene derivatives having a star structure are produced by anionic polymerization of styrene or styrene derivatives with butyl lithium, sodium naphthalene complexes, etc. ,
(tetrachloromethylbenzene, tetrachlorosilane) and further halogenated alkylating agents such as halogenated dimethyl ether, dihalogenated dimethyl ether or (hydrogen halide + formalin) and Lewis such as zinc chloride, iron chloride or boron fluoride. It can be synthesized by halogenated alkylation with acid.

The flattening material of the present invention is used by dissolving the organic polymer represented by (1) or (2) in an aromatic hydrocarbon (toluene, xylene, etc.), an ester compound (ethyl cellosolve acetate, etc.), etc. It becomes a state where The solids concentration in this case is usually 10 to 60% by weight.

The method of using the planarizing material of the present invention is as follows.

First, an insulating film substrate with steps (for example, silicon oxide,
(silicon nitride, polysilicon, etc.) - An organic polymer represented by Funato (1) or (2) is applied to a film thickness of 0.1 to 10 μm by spin coating, spray coating, or the like. Subsequently, the obtained organic polymer film is heated usually at 100 to 240°C using an infrared lamp, a hot plate, a clean oven, etc. to melt and flow it to obtain a flattened surface. The organic polymer film is cross-linked by irradiation with ultraviolet rays or electron beams in order to improve the surface resistance, and then the organic polymer film is dry-etched using a reactive dry etching device to transfer the flat surface to the insulating film, thereby achieving ideal planarization. An insulating film obtained by this method is obtained.

[Function] The present inventors coated various organic film materials on substrates with steps by spin coating, heated them at a constant temperature, and then measured the flattening properties using Talystep. When polystyrene or a polystyrene derivative having a structure is used, flattening properties are significantly improved, and an ideal flat surface can be obtained even when the step width becomes wide.

Figure 1 shows that the flattening material made of polystyrene (weight average molecular weight, 1400) having a star structure according to the present invention was
Coated on a substrate with an initial level difference of 0 and heated at 200℃ for 6 hours.
This figure shows the difference in height remaining in the coating film after heating for 0 minutes.

In addition, for comparison, we also use ordinary linear polystyrene (
The weight average molecular weights (1400 and 16000) are also shown.

With the flattening material of the present invention, an ideal flat surface can be obtained even when the step width becomes wide. This is because the organic polymer with a star-like structure in the present invention has less entanglement between organic polymers in the molten state when heated, compared to organic polymers with a linear structure, so it has excellent fluidity during heating. It is thought that

[Example] Hereinafter, the present invention will be explained in more detail with reference to Examples.
The scope of the invention is not limited by these examples.

Example].

800mm thick SiO□ on top of 6000mm thick semiconductor pattern
A planarizing material of the present invention represented by the following formula (4) was applied to a thickness of 7000 on the substrate with xylene as a solvent. After coating, it was heated at 200° C. for 60 minutes in a nitrogen atmosphere, and then irradiated with deep ultraviolet light for 1 minute in a nitrogen atmosphere to cure it. Next, in a reactive ion etching device, high frequency power 100W, chamber pressure 4.5Pa, CF
Etching was performed under the following conditions: 4 flow rate 30SC:CM, Oz flow Ji 2.5SCCM. After etching, the shape of the coated organic polymer film was directly transferred to the 5tOz film, and the height difference was less than 1000 Å over the conductor width of 500 μm or more, resulting in an almost ideal flat surface.

(Weight average molecular weight: 2000, chloromethylated styrene unit: 40%) Example 2 In exactly the same manner as in Example 1, only the flattening material represented by formula (4) was replaced with the flattening material represented by formula (5). We conducted an experiment. As a result, exactly the same results as in Example 1 were obtained, and the substrate could be planarized.

Very similar results were obtained and the substrate could be planarized.

(Weight average molecular weight 1400, chloromethylated styrene unit 40%) Example 3 In exactly the same manner as in Example 1, only the flattening material represented by formula (4) was replaced with the flattening material represented by formula (6). We conducted an experiment. As a result, Example 1 remained unchanged (weight average molecular weight 1300, chloromethylated styrene unit 40%) [Effect of the invention] If planarization is performed by etchback using the planarization material of the present invention, it does not depend on the step width. An ideal flat surface can be obtained. Furthermore, the planarization material of the present invention can be used as a lower layer material (planarization layer material) in a multilayer resist method in a lithography process in the manufacture of semiconductor integrated circuit devices.

[Brief explanation of the drawing]

Figure 1 shows the flattening material of the present invention and polystyrene.
FIG. 3 is a diagram showing the dependence of level difference flattening on the step width after heating at 00°C. Drawing (μm)

Claims (1)

[Claims] 1. A flattening material comprising polystyrene or a polystyrene derivative having a star-like structure. 2. The flattening material according to claim 1, wherein the polystyrene or polystyrene derivative has a molecular weight of 500 to 10,000. 3. Polystyrene or polystyrene derivatives have a general formula: ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (1) or ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (2) {In formulas (1) and (2), R_1 is , trivalent group, R_
2 is a tetravalent group, R_3, R_4, R_5 and R_6
is a general formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (3) [In formula (3), R_7, R_8 and R_9 are hydrogen atoms, methyl groups or halogen atoms, X is halogen atoms, m and n represents an integer greater than or equal to 0, and cannot be 0 at the same time. ]} The flattening material according to claim 1 or 2, which is an organic polymer having a star-like structure.