JPH0230572B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical Field of the Invention The present invention relates to a multilayer structure, and particularly to electronic devices having fine patterns, such as semiconductor devices and bubble memory devices.

(2) Background of technology As the functions of electronic circuits increase and the degree of integration of the electronic components used in them increases, from individual components to ICs and LSIs, wiring between elements becomes complex and requires many intersections. I'm getting used to it. This necessitated multilayer wiring. We first applied the general formula (H _2-a RaSiO) _o [R is H ₃ SiO,
H ₂ CH ₃ SiO, H(CH ₃ ) ₂ SiO or (CH ₃ ) ₃ SiO
and a is 0 or 1, and the average value in the molecule is in the range of 0 and 1. A patent application has been filed for a method of coating a resin represented by the following formula and thermally decomposing it to form a silicon oxide film, and the present invention applies this resin to an insulating layer of a wiring structure.

(3) Conventional technology and problems Conventionally, interlayer insulation for devices with fine patterns such as LSIs, Josephson devices JJ, and bubble memories has been achieved using silicon oxide (SiO ₂ ) films created by thermal oxidation of silicon substrates, or vapor phase insulation using silane-based gases. This is done using grown SiO ₂ -based insulating materials or organic insulating materials such as polyimide and silicone resin, but these have advantages and disadvantages in terms of miniaturization and reliability. In other words, the current situation is that there is no material that satisfies all of the requirements for interlayer insulation, such as flattening function, heat resistance that can withstand temperatures of 400 to 1000 degrees Celsius in air, and reliability such as adhesion, electrolytic corrosion resistance, and ability to form thick films. .

Currently, SiOx is produced by applying and heat-treating silicone resin, which has excellent flattening function and heat resistance.
Focusing on film formation, polydialkoxysilane
RO [-(RO) ₂ SiO]- _o R [wherein R is a monovalent hydrocarbon, such as CH ₃ , C ₂ H ₅ or hydrogen, and at least 1/3 of OR is an alkoxy group. ] is known to be thermally decomposed into SiO ₂ . The reason why alkoxy groups are left in the molecule is that if all of them are OH, the storage stability will be very poor. If this polydialkoxysilane is thermally decomposed after coating, the alkoxy groups will scatter and leave distortion and pinholes in the coating film, so depending on the type of material, the amount of 0.2 to 0.5μ
If it is applied to a thickness of more than m, cracks will appear in the coating, and if it is applied to a thickness less than that, it will cause electrolytic corrosion defects. Therefore, if a silicone resin exists with very few atoms or atomic groups scattered during thermal decomposition, it should be possible to form an insulating film with excellent flattening function, heat resistance, and reliability as described above. .

(4) Object of the invention The object of the invention is to provide an excellent insulating film that has a flattening function, heat resistance, and reliability in a multilayer wiring structure.

(5) Structure of the Invention The present invention is based on the general formula: R ² O (-R ¹ ₂ SiO) - _o R [wherein R ¹ is entirely H or at least half is H, and the remainder is - OSiH ₃ ,−
OSiH ₂ CH ₃ , −OSiH(CH ₃ ), or −OSi
( _CH3 ) ₃ ; ^R2 _{is -SiH3} , _-SiH2CH3 , -SiH
(CH ₃ ) ₂ or -Si(CH ₃ ) ₃ ; n is 1 to
It is an integer of 100. ] A silicon oxide film having the above-mentioned good flattening function, heat resistance, and reliability can be formed by applying a silicone resin represented by the formula, using a solvent if necessary, and then heating it. By utilizing this, the film is applied as an insulating layer in a wiring structure.

That is, the present invention provides a wiring structure in which an insulating layer and conductive wiring are formed in one or more layers on a substrate, in which all or part of the insulating layer has the general formula: (H _2-a RaSiO) _o [wherein, R is H ₃ SiO, H ₂ CH ₃ SiO, H(CH ₃ ) ₂ SiO
or (CH ₃ ) ₃ SiO, where a is 0 or 1
The average value in the molecule is in the range of 0 and 1. ] H ₃ SiO,
H ₂ CH ₃ SiO, H(CH ₃ ) ₂ SiO or (CH ₃ ) ₃ SiO
Apply silicone resin sealed with 300~
Provided is a wiring structure characterized in that it is formed of a layer heat-treated at 500°C to form SiOx.

The basic principle of the invention is the formula H ₃ SiO(-H ₂ SiO)- _o
If SiOx is formed using silicone resin consisting of _SiH3 , H will be easily decomposed during thermal decomposition.
Since the amount of impurities in the SiOx film is small and the volume of H is small, the volume shrinkage strain after H scattering is small, and the pinholes are also minute, and the increase in volume due to SiO oxidation alleviates the strain and fills the pinhole. , the final result is small strain, dense, and pure SiOx (x=1~
2) A wiring structure having a film can be obtained. As mentioned above, HO(-H ₂ SiO) _-o H is unstable, but it becomes stable when the terminal is silylated, and this makes the device obtained by the present invention practical. . The advantage of this basic principle is not lost even if some CH ₃ is included in the molecule in addition to Si, O, and H. However, it is preferable that substantially all of R ¹ in the molecule of the silicone resin used in the present invention is H, and the proportion of substituents other than H should normally be about 10%, and at most less than 50%. It is.

Silicone resin R ² O (-R ¹ ₂ SiO) used in the present invention
_o R ² has a specific gravity of 1.6 to 1.7, and at room temperature, if n<3, it is a liquid; if n≧3, it is a powder; if it is a liquid, it can be applied as it is, but if it is a powder, it can be applied by rotating, for example. When applying to a substrate by coating (spin coating), it is applied after being dissolved in an organic solvent such as toluene. In the case of spin coating, the film thickness can be adjusted by adjusting the molecular weight, type of solvent, resin concentration, and rotation speed. The appropriate film thickness is in the range of 0.5μ to 1.5μ; if it is larger than that, it will reduce the crack resistance, and if it is smaller than that, it will reduce the insulation effect, but it can be used in combination with other insulating materials. be.

Silicone resin R ² O (-R ¹ ₂ SiO) - _o R ² is spin coating,
Since it can be coated by spraying or other methods, it has the ability to apply to uneven substrates and flatten the surface. Therefore, it is suitable for use as an interlayer insulating material for wiring in semiconductor devices with fine wiring or bubble memories, etc. by preheating at 60 to 300°C and heat treating at 300 to 500°C to form SiOx. Furthermore, those with CH ₃ group at the end are 400
Although it does not change to complete SiOx at temperatures below ℃ or, in some cases, below 470 ℃, it can be used without requiring perfection when used for interlayer insulation.
Thermal decomposition of Si--CH ₃ bonds occurs at temperatures above 300-350°C, but for example, infrared absorption measurements show that CH ₃ groups or Si--C
Reactions can be confirmed by tracking the content of bonds. By repeating coating and heat treatment to form SiOx, a thick film can be obtained, and by filling deep holes and grooves, the flattening function is emphasized and a dense film can be obtained.

In the present invention, the reduction in film thickness due to volumetric shrinkage is only 3 to 10% compared to the usual 50%, and almost no shrinkage is observed.

The insulating resin cured layer in the multilayer wiring structure of the present invention may be a layer combined with SiO ₂ or the like by vapor phase growth.

(6) Examples of the invention (1) Preparation of resin Diethoxysilane was dissolved in methyl isobutyl ketone (MIBK) and water was added to convert it into silanol.
Powdered polysiloxane (CH ₃ ) ₂ HSiO (-H ₂ SiO) - _o SiH (CH ₃ ) ₂ obtained by adding dimethylchlorosilane after condensation polymerization at 35°C for 20 hours, [average value of n was 8. ] is a resin.

Powdered polysiloxane H ₃ SiO (-H ₂ SiO) - _o SiH ₃ [n
The average value was 19] is used as a resin.

The liquids obtained by dissolving resin and resin in toluene are referred to as resin liquid and resin liquid, respectively.

(2) Example 1 A 25% by weight resin liquid was prepared as described above. Next, a bipolar element was formed in the silicon substrate, and a first layer of aluminum wiring was formed thereon. The aluminum wiring has a thickness of 0.9 μm, a minimum line width of 3 μm, and a minimum line spacing of 2 μm. The resin solution was spin-coated at 6000 rpm for 20 seconds, and
Solvent drying was carried out at 450°C for 30 minutes and heat treatment was carried out at 450°C for 60 minutes. The film thickness obtained by coating on a flat plate under the same conditions was 0.8 μm, but it was 0.4 μm on the aluminum wiring, 1.1 μm in the space, and the step difference was 0.2 μm. Next, 1.0 μm PSG is formed by a known method, through holes are formed, a second layer of aluminum wiring is formed, and a protective layer of 1.3 μm is formed.
A bipolar element device was obtained by forming a PSG layer of m and making a window for taking out the electrode. This device has a heating test of 500℃ in air for 1 hour, -65℃←→150℃
No abnormalities or defects were observed after 10 thermal shock tests, 6V application at 85°C and 90% RH, 1000 hours of testing, and a combination of these tests.

(3) Comparative Example 1 An attempt was made to obtain a bipolar element device in the same manner as in Example 1, except that polyimide was applied to the same thickness instead of the resin liquid and cured at 350°C for 30 minutes. , the PSG film peeled off at the stage when it was formed on the polyimide film.

(4) Comparative Example 2 A bipolar element device was obtained in the same manner as in Example 1, except that the interlayer insulating layer and the protective layer were formed of polyimide. When this was subjected to a heat resistance test in nitrogen at 500°C for 1 hour, the polyimide layer turned brown. moreover
When a 6V application test was conducted at 85°C and 90%RH, a large leakage current flowed and part of the polyimide layer peeled off.

(5) Comparative Example 3 A bipolar element was obtained in the same manner as in Example 1, except that a ladder type methylpolysilsesquioxane was applied instead of the resin liquid and cured in nitrogen at 450°C for 1 hour. Ta. This was subjected to a heat resistance test in nitrogen at 500°C for 1 hour and a 6V application test at 85°C and 90% RH, but no defects were found. But 500 in the air
When a heat resistance test was conducted at ℃ for 1 hour, a crack occurred in a part of the electrode window opening.

(6) Example 2 Same as Example 1, but after applying 18% resin liquid on the first layer of aluminum wiring and hardening, apply resin liquid again and harden, then after forming through holes, Layered aluminum wiring was performed. The protective layer on top is also formed using resin liquid,
An electrode extraction window was formed to obtain a bipolar device. This semiconductor device was subjected to the test described in Example 1, but no abnormalities or defects were found.

(7) Example 3 SiO ₂ of 1000 Å was deposited on a GGG (gallium gadolinium garnet) substrate on which an LPE (liquid phase epitaxial) layer was formed for bubble generation.
formed a layer. A conductor pattern consisting of an Al layer with a thickness of 4000 Å was formed thereon. The line width of the conductor pattern is 1 to 50 μm, and the space is 1 to 50 μm.
It was 100 μm.

Next, using a resin liquid with a concentration of 15%, the speed was set at 4000 rpm.
Spin coating was performed for 30 seconds, and solvent drying was performed at 60°C for 30 minutes. At this stage the resin is soluble in the solvent. Then, curing was carried out in air at 350°C for 60 minutes. When applied to a flat substrate under the same conditions, the thickness of the resin film was 0.35 μm. Furthermore, a permalloy pattern with a thickness of 4000 Å is formed, and a resin liquid is applied on top of it.
Spin coating was performed at 3000 rpm for 30 seconds, and after drying the solvent, curing was performed at 300° C. for 180 minutes in nitrogen. The thickness is 0.4 μm on a flat substrate. A 0.4 μm thick SiO ₂ layer was formed thereon by sputtering. A bubble memory was obtained by dry etching the two insulating layers using a reactive gas of CF ₄ --O ₂ (5%). Incubate the resulting bubble memory at 85℃, 90%
Although a DC voltage of 300V was applied between the permalloy pattern and the conductor pattern for 100 hours in a RH environment, insulation failures continued to occur. The normal operating voltage of this bubble memory is a maximum of 24V, and it was found to have excellent reliability.

(8) Comparative Example 4 Same as Example 3, except that a polydiethoxysiloxane solution was applied as an insulating layer between the conductor and permalloy, and treated in air at 350°C for 60 minutes to a thickness of 3500 Å (on a flat substrate). form _two layers of SiO,
The thickness of the permalloy layer is 10,000 mm due to spats.
_Two layers of SiO were formed. When this bubble memory was subjected to the same electrolytic corrosion test as in Example 3, insulation failure occurred after 48 hours.

(7) Effects of the Invention According to the present invention, since a heat-resistant and reliable coating resin can be used for insulation between wiring layers, a highly reliable multilayer structure can be obtained.

Claims (1)

[Claims] 1. A wiring structure comprising one or more layers of an insulating layer and conductive wiring on a substrate, in which all or part of the insulating layer has the general formula: (H _2-a RaSiO) _o [ In the formula, R is H ₃ SiO, H ₂ CH ₃ SiO, H(CH ₃ ) ₂ SiO
or (CH ₃ ) ₃ SiO, where a is 0 or 1
So, the average value of a in the molecule is in the range of 0 and 1. ]
The ends of the polysiloxane represented by H ₃ SiO,
H ₂ CH ₃ SiO, H(CH ₃ ) ₂ SiO or (CH ₃ ) ₃ SiO
Apply silicone resin sealed with 300~
A wiring structure characterized by being formed of a layer heat-treated at 500°C to form SiOx.