JPH02277255A - Semiconductor device - Google Patents

Abstract

PURPOSE:To increase a heat-resisting property and to enhance reliability by a method wherein an interlayer insulating film is formed of a specific phenyl silicone ladder polymer whose end is a hydroxyl group. CONSTITUTION:The following are provided: a semiconductor substrate 1 composed of silicon; a protective film 2 composed of plasma SiN; an interlayer insulating film 4; a contact hole 5 which has been formed in the interlayer insulating film 4 by a photolithographic technique. The interlayer insulating film 4 is formed of a phenyl silicone ladder polymer whose end is a hydroxyl group as expressed by Formula I. In Formula I, (n) represents an integer of 2 to 1000. In addition, a film thickness of the interlayer insulating film 4 is prescribed by a thickness of an electrode layer to be insulated; however, it is preferable that the film is formed in a thickness of 1.0 to 3.0mum in order to keep a good balance among a stray capacitance, a flat property and a processing property. Thereby, a heat-resisting property is excellent; a characteristic is not deteriorated even when an upper-layer wiring part is formed; reliability can be enhanced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a semiconductor device having a multilayer wiring structure of two or more layers. More specifically, the interlayer insulating film (in the formula, 4 R3s are the same or different and each is a hydrogen atom, a methyl group, or an ethyl group, and 20 R2s are the same or different, and more than half of the R2s are methyl groups). , the remaining R2 is an ethyl group, phenyl group, chlorophenyl group, hydroxy group, methoxy group or ethoxy group, and n is 15
00 to 200,000, an integer sufficient to give a molecular weight of from 0.00 to 200,000.

The ladder organopolysiloxane represented by the structural formula [1] has a ratio of the number of silicon atoms to the number of oxygen atoms of approximately 1:1.5, and a ratio of the number of silicon atoms to the number of side chains of approximately 1:1.
:1, which is different from the linear polysiloxane conventionally used as a protective resin for semiconductor devices, and because the siloxane has a ladder structure, it has excellent heat resistance. Structural formula (1
) Among the ladder-type organopolysiloxanes represented by the formula (■), it is often used that all of the side chains R2 are methyl groups, or more than half are methyl groups and the remainder are phenyl groups, especially those with the structural formula (■): ( Ladder organopolysiloxanes are often used, where n is an integer sufficient to provide a molecular weight of 1,500 to 200,000.

[Problem to be solved by the invention] According to Japanese Patent Application Laid-open No. 58-49540, structural formula (II
When R2 of Il is an ethyl group, a propyl group, or a phenyl group, the thermal decomposition temperature is approximately 350.320.400°C, respectively.
In the case of methyl, it is indicated as 700-740°C.

However, according to experiments conducted by the present inventors, it was found that the methyl group has a heat resistance of only 450°C at most.

Therefore, semiconductor devices that use conventional ladder-type organopolysiloxanes with methyl groups in their side chains as interlayer insulating films have low heat resistance and cannot withstand the processing temperatures used in the process of forming upper layer wiring. This poses a problem in that the reliability of the semiconductor device is low.

On the other hand, a plasma SlN film is also used as an interlayer insulating film that can be formed at a relatively low temperature and has a relatively high dielectric strength voltage. However, this method has a problem in that hillocks occur in the A# electrode film due to thermal effects during the formation of the SIN film.

The present invention has been made in view of the above-mentioned problems, and an object of the present invention is to provide a highly reliable semiconductor device having an interlayer insulating film having high heat resistance and good flatness.

[Means for Solving Problem 8] The semiconductor device of the present invention is a semiconductor device having at least a two-layer wiring structure, in which the interlayer insulating film has the structural formula (I): (where jl is 2 to 1000) It is characterized by being formed from a phenyl silicone ladder polymer with a terminal hydroxyl group represented by (integer).

[Function] Since the heat resistance of the phenyl silicone ladder polymer with terminal hydroxyl groups in the present invention is about 550°C, the heat resistance of the interlayer insulating film can be improved, and the high-temperature characteristics of the semiconductor device can be improved.

[Embodiment 1] Hereinafter, a semiconductor device of the present invention will be explained based on the drawings, but the present invention is not limited to such embodiments.

1(a) to 1(e) are schematic explanatory diagrams of the procedure for forming an interlayer insulating film according to the present invention.

In Figure 1 (ω~1(e)), (1) is a semiconductor substrate made of silicon, (2) is a protective film made of plasma SIN (II), (4) is an interlayer insulating film, and (5) is an interlayer insulating film. This is a contact hole formed in the film (4) by photolithography.The interlayer insulating film (4) has a terminal end represented by the structural formula (I): It is formed from a hydroxyl phenyl silicone ladder polymer.If n is an integer from 2 to 1000, it will exhibit the specified insulation properties without impairing the flatness even at a service temperature of 500°C, but from the viewpoint of crack resistance, n is preferably an integer of 30 or more. If n is less than 1, oligomers will form, resulting in poor solution stability;
If it exceeds o, it becomes difficult to dissolve in the solvent, which is not preferable.

The film thickness of the interlayer insulation m (4) is determined by the thickness of the electrode layer to be insulated, but it is formed to a thickness of 1.0 to 3.0 times in consideration of stray capacitance, flatness, and workability. is preferable. Further, as the film forming method, methods such as dip printing and screen printing can be adopted, but from the viewpoint of flatness and uniformity, it is preferable to use a spin code method.

When forming a film by the spin code method, the phenyl silicone ladder polymer with terminal hydroxyl groups is dissolved in a solvent and applied. The solvent to be used is preferably anisole from the viewpoint of safety, but from the viewpoint of solubility due to molecular weight, aromatic hydrocarbon solvents such as toluene, xylene, and benzene, ketone solvents such as methyl ethyl ketone and acetone, tetrahydrofuran, diethyl ether, and isopropyl. Ether solvents such as ether, ethyl cellosolve, N-methylpyrrolidone, and the like can be suitably used.

The rotation speed of the spin cord is appropriately selected depending on the concentration of the solvent and solution used. For example, when the solvent is anisole and the concentration is 15% by weight, the rotation speed is 350 O.
rpm. The reason why the concentration and rotation speed are defined in this way is that a uniform coating can be achieved with a film thickness of about 1.5 mm.

Phenyl silicone ladder polymers with terminal hydroxyl groups are usually N
a, K, re, CuSPb, IIC#, U
Although it contains impurities of Na and Th, from the point of view of reliability.
, K., Pe.

Less than 1 ppm for Cu, Pb, HCN;
Regarding U%T11, it is preferable that it is less than 11)I)b.

Contact holes (5) are formed at predetermined locations in an interlayer insulating film (4) formed on a semiconductor substrate (1) having circuit elements to form a multilayer wiring.

This contact hole (9) is formed using an interlayer insulating film (4).
This is done by applying a resist in a predetermined pattern thereon, and then removing the interlayer insulation m (4) at a predetermined location by etching. The resist used is not particularly limited, but from the viewpoint of versatility, it is preferable to use a cresol novolak resist. Further, from the viewpoint of etching speed and accuracy, it is preferable to use anisole or xylene as the etching solution.

After the contact hole (5) is formed, the resist is removed using n-butyl acetate and heat treatment is performed.

The interlayer insulating film (4) is cured. The heat treatment conditions are preferably 300'C or higher from the viewpoint of dehydration condensation reaction of terminal hydroxyl groups, and particularly preferably 350'C or higher from the viewpoint of complete curing.

Formation of contact hole (5) and interlayer insulating film (4)
After curing, a second electrode is formed, and the above procedure is repeated to form a second interlayer insulating film (4) having a predetermined contact hole (5).

By repeating this procedure, a semiconductor device having a desired multilayer electrode can be produced.

Example 1 A silicon nitride protective film (10 cm in diameter) having a circuit element covered with a silicon nitride protective film (21) with predetermined portions exposed.

A silicon wafer (1) with a thickness of 0.5 am was prepared, and an M wiring layer with a thickness of about 1 channel was formed in a predetermined pattern on the circuit elements of this silicon wafer (1) (first (ω diagram)). )reference). After that, Na, K, Pa, Cu%
Each content of pb and II C1 is 1 ppm
and the content of each of U and Th is 11)
I) Structural formula (lit) which is less than b.

A high-purity phenyl silicone ladder polymer represented by is added to anisole to make a solution with a concentration of about 15% by weight, and this solution is placed on the silicon urethane (1) at a rotation speed of 30%.
Coating was performed using a spin code method at 00 rpm and 1 m. Thereafter, heat treatment was performed at a temperature of 250° C. for 30 minutes in a nitrogen atmosphere to form a first layer of interlayer insulating film (4) (see figure 1). The film thickness at that time was 1.5 mm.

The obtained interlayer insulating film (4) is made of 0FPR manufactured by Tokyo Ohka Kogyo ■.
After applying a resist consisting of 800 nitride in a predetermined pattern, etching was performed using anisole and xylene under conditions of anisole/xylene -1/2 to form an interlayer insulating film (4
) A desired contact hole (5) was drilled on the top. Thereafter, the resist was removed using n-butyl acetate, and heat treatment was performed at a temperature of 350° C. for 60 minutes in a nitrogen atmosphere to pattern contact holes (5) and harden the interlayer insulating film (4). (See Figure 1(C)).

N electrode 1i! A semiconductor device having a multilayer electrode was fabricated by repeating the formation of i (3), the formation of an interlayer insulating film (4), and the drilling and patterning of contact holes (5) (1 (d) to 1 (e)). ) see figure).

About the obtained semiconductor device 20V x 10001
The presence or absence of corrosion due to the interlayer insulating film (4) was investigated by applying electricity under the condition of 1r, but no corrosion was observed. In addition, the presence or absence of N hillocks during molding of interlayer insulation 1/f4) was investigated, but no hillocks were observed. Furthermore, in order to investigate the heat resistance, a high temperature test of 400° C. x 100 hours was conducted on the substrate, but no abnormality was observed.

[Effects of the Invention] As explained above, according to the present invention, the interlayer insulating film is formed using a high-purity, highly heat-resistant phenyl silicone ladder polymer. A highly reliable semiconductor device whose characteristics do not deteriorate can be obtained.

[Brief explanation of drawings]

1(a) to 1(e) are cross-sectional views of a semiconductor device according to an embodiment of the present invention. (Main symbols in the drawing) (1): Semiconductor substrate (2): Protective film (3); Wiring layer (4): Interlayer insulating film (5): Contact hole agent Yu Iwamasu, Nihon University, 1st (d) mouth contact Ho

Claims (1)

[Claims] (1) A semiconductor device having at least a two-layer wiring structure, in which the interlayer insulating film has a structural formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼(I) (In the formula, n is an integer from 2 to 1000. 1. A semiconductor device characterized in that it is formed of a phenyl silicone ladder polymer with a hydroxyl terminal group represented by the following formula.