JPH05163353A - Organosilicon polymer and production of semiconductor device - Google Patents

Abstract

PURPOSE:To provide an organosilicon polymer, a process for producing an interlayer insulation film made therefrom and an insulation material excellent in heat resistance and leveling properties. CONSTITUTION:A process for producing a semiconductor device comprising forming an organosilicon polymer which is a polymer of a weight-average molecular weight of 3000-5000000 represented by the general formula [RASiO2/2(RB)1/2]n (wherein at least 20% of RAs are hydroxylated aryl groups, the rests are lower alkyl groups; RB is alkylene; n is an integer of 10-50000, wherein the hydrogen atoms of the silanol groups contained in the polymer are substituted by triorganosilyl groups of the general formula (RC)3Si(wherein Rs are epoxy, lower alkyl or aryl and may be the same or different from each other), either forming an interlayer insulation film of a semiconductor integrated circuit from the polymer or forming an interlayer insulation film of a semiconductor integrated circuit by adding naphthoquinonediazide to the organosilicon polymer to form a photosensitive heat-resistant resin composition and forming an interlayer insulation film of a semiconductor integrated circuit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic silicon polymer and a method for forming an interlayer insulating film of a semiconductor integrated circuit using the same.

Since it is necessary to process a large amount of information at a high speed, the semiconductor devices forming the main body of an information processing apparatus have been highly integrated, and LSI and VLSI have been put into practical use, and further, ULSI has been put into practical use. ..

Here, the integration is performed by miniaturization of the unit element which constitutes the element rather than by increasing the size of the chip, and the minimum line width of the wiring has reached sub-micron. Also, the electronic circuit has a multilayer structure with an interlayer insulating film interposed.

Therefore, the material for forming the interlayer insulating film is required to have excellent heat resistance and flatness of the underlying layer.

[0005]

2. Description of the Related Art In the manufacture of semiconductor integrated circuits, a large number of electrodes, wirings, etc. are multilayered on a semiconductor substrate. The presence of this step significantly lowers the reliability of the multilayer wiring.

Therefore, a necessary condition of the interlayer insulating film is that it has excellent flattening property in addition to excellent electrical insulating property and heat resistance. Here, as the material for forming the interlayer insulating film, there are inorganic and organic insulators.

That is, as the inorganic insulating material, silicon dioxide (SiO ₂ ), silicon nitride (Si ₃ N ₄ ), phosphosilicate glass (abbreviated as PSG) is used.
The film is formed on the substrate to be processed by a vapor phase growth method (CVD method) or the like.

However, although these insulating films have excellent characteristics such as electrical characteristics and heat resistance, they do not meet the purpose of planarization because they faithfully reproduce the irregularities of the underlying substrate during formation.

Therefore, an inorganic insulating film is formed by a CVD method or the like, and then an organic insulating material is applied to planarize it, and then dry etching is performed until the inorganic insulating film appears to obtain a flat surface. A bias sputtering method has been proposed in which the inorganic insulating film is formed and the sputtering is performed at the same time to form a film while scraping the protrusions to obtain a flat surface. However, it is a practical method because it requires a large number of steps. It can not be said.

On the other hand, as the organic insulator, there are polyimide resin and silicon resin, and the coating liquid obtained by dissolving this in a solvent can form a film on the substrate by the spin coating method, and therefore has excellent flatness. But there are some problems.

That is, the polyimide resin is decomposed at about 450 ° C., has a high hygroscopic property, and has a drawback that it contains corrosive impurities such as alkali metals. Further, the silicon resin has a drawback that it is easily oxidized at a temperature of about 400.degree. C. or thermally decomposed at a temperature of 500.degree.

From these facts, the heat resistance is excellent, and
It is desired to develop an organic insulating material having high purity and low hygroscopicity.

[0013]

When forming an integrated circuit such as VLSI or ULSI that requires multi-layer wiring, it has excellent heat resistance,
In addition, an interlayer insulating film having excellent substrate flatness is required.

Further, when a multilayer wiring structure is adopted, it is necessary to provide a via-hole through the interlayer insulating film and connect the upper and lower wirings to the circuit. The organic insulating material itself has photosensitivity rather than selectively etching the via hole formation part by coating with, and contributes to shortening the process if only the ultraviolet irradiation part becomes solvent soluble There is a lot to do.

Therefore, development of such a material is an issue.

[0016]

[Means for Solving the Problems]
A polymer represented by (1) and having a weight average molecular weight of 3,000 to 5,000,000, wherein the hydrogen atom of the silanol group contained in the polymer is replaced by a triorganosilyl group represented by the following general formula (2). The organic heat-resistant resin composition is prepared by forming an organic silicon polymer and forming an interlayer insulating film of a semiconductor integrated circuit using this, or by adding naphthoquinone diazide to this organic silicon polymer. This can be solved by configuring a method for manufacturing a semiconductor device, which is characterized in that an interlayer insulating film of a semiconductor integrated circuit is formed by using this.

[ ^RA SiO _2/2 (R ^B ) _1/2 ] _n ... (1) where R ^A is 20% or more of the hydroxy-substituted aryl group, the rest is a lower alkyl group, R ^B is an alkylene group, n
It is an integer of _{^{10~5,0000, (R C) 3 Si-}} ···· (2) where, R ^C is an epoxy group may be the same or different represents a lower alkyl group or an aryl group.

[0018]

The present inventors have improved the conventional organic silicon polymer having a ladder-type siloxane structure as a method for satisfying the above requirements.

That is, 1,4-bis (dihydroxymethylsilyl) methane is dissolved in methyl isobutyl ketone and subsequently condensed under reflux conditions while removing water produced, thereby forming a siloxane such as dimethylsilalkylenedisiloxane. Organic silicon polymers having alternating bonds and silalkylene bonds are known, but the organic silicon polymer according to the present invention comprises 20% or more of lower alkyl groups with hydroxy-substituted aryl groups, and The hydrogen (H) atom of the silanol group contained in is substituted with a triorganosilyl group.

Structural formulas (3) and (4) are rewritten general formulas of general formulas (1) and (2) to facilitate understanding, and take either structure.

[0021]

[Chemical 1]

[0022]

[Chemical 2]

In this structural formula, 20% or more of R ^A is a hydroxy-substituted aryl group such as C ₆ H ₄ (OH), C ₆ H ₃ (OH) ₂ and the rest is CH ₃ , C ₂ H ₅ , nC ₃ H ₇ , iC ₃ H ₇ , C ₆ H ₅ , C ₆ H ₄ -C
A lower alkyl group such as H ₃ .

R ^B is an alkylene such as —CH ₂ —, —C ₂ H ₄ — and R ^C is an epoxy group, a lower alkyl group or an aryl group. The organic silicon polymer according to the present invention is a polyorganosyl alkylene siloxane having such a structure, but the ratio of the sil alkylene bond and the siloxane bond in the molecular chain may be any, and the insulating film In order to prevent the occurrence of cracks, it is preferable to have 25% by weight or more of alkylene bonds.

When the interlayer insulating film is formed using such an organic silicon polymer, cracks are not generated because the stress due to the thermal expansion of the wiring material is not easily received. The next feature is that a photosensitive resin composition can be formed by adding naphthoquinonediazide to this material, and alkali development becomes possible.

That is, in the polyorganosylalkylene siloxane according to the present invention, R ^A shown in the general formula (1) is 20
% Or more have hydroxy-substituted aryl groups such as C ₆ H ₄ (OH) and C ₆ H ₃ (OH) ₂ and are soluble in alkali developers such as tetramethylammonium hydroxide (abbreviated as TMAH). However, a positive resist can be formed by adding naphthoquinone diazide to this.

[0027] That is, in a state of not performing light irradiation polyorganosiloxane silalkylenesiloxane according to the present invention by the dissolution inhibiting effect of the naphthoquinone diazide is insoluble in an alkali developer, naphthoquinonediazide by light irradiation left the N ₂ To form carbene, which reacts with water through ketene to be converted to a carboxylic acid and becomes alkali-soluble.

The polyorganosylalkylene siloxane becomes alkali-soluble in order to lose its dissolution inhibiting effect. As described above, the photosensitive resin composition obtained by adding naphthoquinonediazide to the polyorganosylalkylenesiloxane according to the present invention can form a positive resist, and the use thereof facilitates the formation of via holes.

[0029]

【Example】

Synthesis Example 1: (Related to Claim 1) To a four-necked flask having a capacity of 300 cc, 100 cc of methyl isobutyl ketone and 30 cc of water were added, 15 cc of triethylamine was added as a catalyst, and 1,4-bis (1,4-bis) bis (bisphenol) was added at room temperature while stirring. (
10 g of hydroxyphenyldichlorosilyl) ethane was dissolved in 50 cc of tetrahydrofuran and added dropwise over 40 minutes.

After completion of the dropping, the reaction system was kept at 80 ° C. and stirring was continued for 2 hours. After the reaction was completed, the mixture was cooled to room temperature, and then washed with a large amount of water until the aqueous layer became neutral.

After removing the water remaining by azeotropy from the washed reaction solution, 20 cc of pyridine was added as a catalyst, and 40
After heating to 0 ° C., 20 cc of glycidylepoxydimethylisocyanatosilane was added and reacted at this temperature for 5 hours to replace hydrogen atoms of unreacted hydroxyl groups.

After the reaction was completed, the reaction solution was poured into a large amount of water to precipitate the resin, and the resin was recovered. The precipitate-collected resin was freeze-dried to obtain 5.5 g of white powder. The weight average molecular weight of this organic silicon polymer determined by gel permeation chromatography and converted into polystyrene was 5.2 × 10 ⁴ .

This resin was dissolved in methyl isobutyl ketone to make a 25 wt% resin solution. Synthetic Example 2: (Related to Claim 3) A 25 wt% solution of the organosilicon polymer having a weight average molecular weight of 5.2 × 10 ⁴ formed in Synthetic Example 1 in a solution of 25% by weight methylisobutylketone was used.
A photosensitive resin liquid was prepared by adding naphthoquinonediazide in a weight percentage. Example 1 (Related to Claim 2) A semiconductor element is formed and Si having a first layer of Al wiring is formed.
The 25 wt% resin solution obtained in Synthesis Example 1 was spin-coated on the substrate to a thickness of 1.5 μm.

The thickness of the Al wiring is 1 mm, the minimum line width is 1 μm, and the minimum line interval is 1.5 μm. After application, the resin liquid is dried at 80 ° C for 20 minutes and then in a nitrogen (N ₂ ) stream at 450 ° C.
Was heat-treated for 1 hour.

The step on the substrate surface after the heat treatment was about 0.2 μm, and the step caused by the wiring was flat. Next, a via hole is formed in this insulating film by using a photo-etching technique that uses a resist, a second layer of Al wiring is formed on it, and a 1.2 μm-thick PSG film is formed as a protective layer by the atmospheric pressure CVD method. Then, a window for taking out an electrode was opened to obtain a semiconductor device.

No defect was found in this semiconductor device even after a heating test at 450 ° C. for 1 hour in the air and a thermal cycle test of 10 times at −65 ° C. to + 150 ° C. Example 2 (Related to Claim 4) A semiconductor element is formed, and a first layer of Al wiring is applied to Si.
The photosensitive resin solution obtained in Synthesis Example 2 was spin-coated on the substrate to a thickness of 1.5 μm.

Here, the thickness of the Al wiring is 1 mm, the minimum line width is 1 μm, and the minimum line interval is 1.5 μm. After application, the resin liquid is dried at 80 ° C for 20 minutes and then in a nitrogen (N ₂ ) stream at 450 ° C.
Was heat-treated for 1 hour.

The step on the substrate surface after the heat treatment was about 0.2 μm, and the step caused by the wiring was flattened. Next, the resin film is exposed to ultraviolet rays using a g-line with a wavelength of 463 nm at a via hole formation position of about 100 mJ / cm ² and then immersed in a TMAH alkaline developer to form a via hole with a diameter of 0.2 μm. After that, naphthoquinonediazide was decomposed and removed by drying and treatment at 450 ° C. for 1 hour in N ₂ stream.

Next, a second layer of Al wiring is formed on this,
A 1.2 μm-thick PSG film was formed as a protective layer by atmospheric pressure CVD, and then a window for taking out electrodes was opened to obtain a semiconductor device.

No defects were found in this semiconductor device even after a heating test at 450 ° C. for 1 hour in the air and a thermal cycle test of 10 times at −65 ° C. to + 150 ° C.

[0041]

By carrying out the present invention, it is possible to obtain an interlayer insulating film which is excellent in heat resistance and flatness and does not cause cracks, and by adding naphthoquinonediazide to the organic silicon polymer according to the present invention. A resin composition having photosensitivity can be obtained, and by using this, an interlayer insulating layer having a via hole can be easily formed.

Claims (4)

[Claims] 1. A polymer represented by the following general formula (1) and having a weight average molecular weight of 3,000 to 5,000,000, wherein the hydrogen atom of the silanol group contained in the polymer is represented by the following general formula (2): An organic silicon polymer characterized by being substituted with a triorganosilyl group represented. [ ^RA SiO _2/2 (R ^B ) _1/2 ] _n ··· (1) However, 20% or more of R ^A is a hydroxy-substituted aryl group, the rest is a lower alkyl group, and R ^B is an alkylene. radical, n is an integer of _{^{10~5,0000, (R C) 3 Si-}} ···· (2) where, R ^C is an epoxy group may be the same or different represents a lower alkyl group or an aryl group. 2. A method of manufacturing a semiconductor device, comprising forming an interlayer insulating film of a semiconductor integrated circuit by using the organic silicon polymer according to claim 1. 3. A photosensitive heat-resistant resin composition obtained by adding naphthoquinonediazide to the organic silicon polymer according to claim 1. 4. A method of manufacturing a semiconductor device, which comprises forming an interlayer insulating film of a semiconductor integrated circuit using the photosensitive heat-resistant resin composition according to claim 3.