JPS58223334A - Method for flattening an uneven substrate - Google Patents

Abstract

PURPOSE:To flatten an undulating substrate efficiently by using a resin liquid, which can cure at a temperature of 25 deg.C or more and displays flowability under the state in which a solvent is not made contain before curing. CONSTITUTION:An Si substrate 11 to which an Si dioxide layer 12 is formed is heated for ten min at 700 deg.C in an oxygen atmosphere, and the resin liquid of which a diarylphthalate resin, a diarylphthalate monomer and a dicumyl peroxide are dissolved in diacetone-alcohol at melting temperatures and filtered by a filter is rotary-applied. The resin is cured through heat treatment for sixty min at 80 deg.C in a nitrogen atmosphere in order to produce flowability to form a resin layer 16. Plasma whole-surface etching using oxygen as a reaction gas is executed. A diarylphthalate layer 17 is left only in the recessed section of the Si dioxide layer. The Si dioxide layer is etched through plasma treatment using C3 F, and an Si dioxide buried layer 12' is formed through plasma treatment.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a method for planarizing an uneven substrate of a semiconductor device, and particularly to a method for planarizing an uneven substrate for insulating and separating between elements or wiring layers of a semiconductor device. This relates to a method of flattening.

(2) Background of the Technology In semiconductor devices, it is necessary to prevent electrical influences between elements or between interconnects. The methods basically include PN junction separation, insulation layer separation, air layer separation, and other separation methods using combinations of these.

(3) Problems with the Prior Art As a method for planarizing a textured substrate using separation using an insulating layer as described in AtJ, for example, first a silicon dioxide (S102) layer and The second method is to form a layer of phosphorus-doped polyester resin (PSG), and the second method is to use a resist material such as phenolic or acrylic, or a heat-resistant resin such as polyimide or polysilsesquioxane as an insulating material. The third method is to apply and cure the above-mentioned heat-resistant resin on the silicon dioxide layer by the above-mentioned vapor phase growth method, and then first remove the upper layer of the heat-resistant resin by etching the entire surface. Then, a portion of the silicon dioxide layer on the protrusion is removed.

A method for obtaining a flat insulating separation layer is known.

In the first method, when the groove width (hereinafter referred to as space) of the uneven substrate is 0.5 μm or less, the effect of flattening the uneven substrate is recognized. However, if the space of the uneven substrate exceeds 0.5 .mu.m, if the spacing exceeds at least 1.5 .mu.m, step coverage will be good and the planarization effect will be lost.

In addition, in the second method, since an organic resin is used as the insulating layer, the heat resistance is limited, and if the width of the space and the protruding part (hereinafter referred to as line) of the uneven substrate is 5 μm or more, the flattening effect is small and it becomes rough. If the thickness exceeds 10 .mu.m, the unevenness of some boundaries between lines and spaces may be maintained, but effective flattening will not be achieved. That is, conventionally, the above-mentioned resist material and heat-resistant resin were formed into a layer by spin coating, and the resin content of the resin liquid was 5 to 40 volumes, and the remainder was organic liquid, and the remaining resin after evaporation was kept at room temperature ( It had the property of becoming solid at temperatures below 30°C.

The state of the resin surface during the process of drying such a resin liquid is schematically shown in FIGS. 1A and 1B. According to FIG. 1A, there is a line 2 on the substrate 1 and a width of 1 μm.
A resin liquid 3a having a narrow space 4 with a width of 12 μm, a wide space 5 with a width of 12 μm, and a resin content of 20 volumes is shown.

In Fig. 1A, the surface of the resin liquid 3a is horizontal after the resin liquid 3a has been spin-coated, but as the solvent in the resin liquid dries, as shown in Fig. 1B, the surface of the resin liquid 3a is horizontal. Irregularities were formed on the surface of the resin layer, and although the irregularities (steps) varied depending on the resin solution, it was impossible to flatten the surface to about 1000 to 0000X. In the case of the present invention, a flat resin layer 6 is formed as shown in FIG.

With the third method, the problem with the second method has not been resolved, and as with the previous method, planarization of a wide space part of 10 μm or more can be achieved using other methods, such as masking the wide space part. I had to resort to etching the entire surface.

(4) Object of the Invention The object of the present invention is to provide a method for flattening an uneven substrate having grooves having a width of at least 10 μm or more, which avoids the above-mentioned drawbacks.

(5) Structure of the Invention The object of the present invention is to form an insulating layer having a thickness equal to or greater than the depth of the groove on the surface of the uneven substrate having at least one groove having a width of 10 μrnμ, Applying a resin liquid on the insulating layer 1~ Curing the resin liquid by heating to form a resin layer, and etching to form a flat substrate having an insulating layer in the grooves of the substrate. Flattening of the uneven substrate. This is achieved by a method for planarizing an uneven substrate, which is characterized in that the resin liquid is a resin liquid that can be cured at a temperature higher than room temperature and exhibits fluidity in a solvent-free state before curing.

That is, in the present invention, even if the width of the groove in the insulating layer having an uneven shape formed on the uneven substrate is 10 μm or more, the width of the groove is 10 μm or less on the insulating layer.
A substantially horizontal resin layer is formed before the entire surface etching step. By forming such a resin layer, it becomes possible to perform uniform etching in the thickness direction by etching the entire surface of the resin layer, and finally it becomes possible to flatten the uneven substrate.

When the ambient temperature is 25° C. or lower, it is preferable to use a liquid resin, and suitable resins include oily polybutadiene and epoxy 4tJll. In addition, if the ambient temperature exceeds 25℃, the melting temperature will be 40℃.
It is preferable to use a resin having a resin concentration of 40% or more, and suitable resins include epoxy resin, diallyl phthalate resin, etc. Furthermore, the melting temperature is 4
The temperature exceeds 0℃, and the thermosetting temperature is 5 degrees higher than the melting temperature.
It is preferable to use a resin with a temperature higher than 0°C, and examples of resins that can be used for this include polyimide of the cross-polymerization type with a molecular weight of 1500 or less. Furthermore, a silicone resin (
R is a monovalent hydrocarbon group, a is a positive number between 1 and 2, and b is 1
and 1.5) is preferably used.

(6) Examples of the invention Embodiments of the present invention will be described below based on the drawings.

Assuming isolation between semiconductor devices, holes with a depth of 0.8 μm and widths of 1, 2.5, and 10.50 μm are drilled in the silicon substrate 11 by dry etching, and then holes with a thickness of 1 μm are formed by vapor phase growth. A silicon dioxide layer 12 was formed. A schematic sectional view thereof is shown in FIG. 3A. 1.3, 14 in Figure 3A
, 15 have widths of 1, 2 . and 50 μm holes are shown.

Next, as shown in FIG. 3A, the silicon substrate 11 on which the silicon dioxide layer 12 was formed was heat-treated at 700° C. for 10 minutes in an oxygen atmosphere, and then diallylphthalate resin DAP 100 L (Osaka Soda) having a melting temperature of about 50° C. ), 5 g of diallyl phthalate monomer DAP100 monomer (manufactured by Osaka Soda), dicumyl, and 0.3 g of f-oxide were dissolved in log diacetone alcohol, and the resin solution was filtered under pressure through a 0.2 μm mesh filter at a rotation speed of 6QOOr.
pm, and heat-treated at 80° C. for 60 minutes in a nitrogen atmosphere to improve fluidity. Then the heat treatment temperature was increased to 20
The temperature was raised to 0° C. and a heat treatment was performed for 60 minutes to harden the resin and form a resin layer 16 as shown in FIG. 3B.

As a result of measuring the surface roughness of the resin layer using a surface roughness meter, the width was 5.
The resin surface formed over the 0 μm hole was 0.05 μm lower than the other resin surfaces, but the other parts were almost flat. Next, plasma etching is performed on the entire surface using oxygen as a reactive gas, leaving diallylphthalate layer 17 only in the concave portions of the silicon dioxide layer, as shown in Figure 3C, and then C3F8 is etched as shown in Figure 3D. The silicon dioxide layer was etched by plasma treatment, and further plasma treatment was performed to form a buried silicon dioxide layer as shown in FIG. 3E. In this way, the hole 15 whose groove width is larger than 10 μm
Similarly to the method 13゜14 where the groove width is smaller than 10 μm, the silicon dioxide buried layer 1 is simultaneously formed using the resin liquid described above.
2' could be formed.

Example 2 Polybutadiene B200 which is liquid at room temperature as resin liquid
Separation between elements was performed by the same process as in Example 1 using a 80% toluene solution of 0 (Japan Petrochemical System). The heat treatment conditions for the resin are 80℃ in a nitrogen atmosphere 30
The temperature was 150° C. in air for 60 minutes, and as a result, a silicon dioxide-embedded ring similar to that of Example 1 could be formed flat.

Example 3 10 g of silanol-terminated polymethylsiloxane obtained by adding 0.5% aqueous hydrochloric acid to trimethyljethoxysilane and refluxing at 85°C, 5 g of triethylamine hydrochloride, and 12 methyltrichlorosilane! :I.

Mix 3 g of vinyltrichlorosilane with 1 g of methyl isobutyl ketone (MIBK) and 30 g of ice-cold water.
was added dropwise with stirring, and then reacted at reflux temperature for 2 hours, washed with water, and the solvent was removed under reduced pressure. The resulting liquid resin was dissolved in toluene to obtain a resin liquid with a solid content concentration of 70%. This resin liquid was applied to the above substrate by a spin coating method, dried at 100°C for 20 minutes, and then heated at 360°C for 30 minutes in nitrogen. Then (
By performing plasma light etching using J(F, -02 (10%)) as a reactive gas, it was possible to form a flat silicon dioxide embedded j- in a hole in a silicon substrate.

Example 4 A silicone resin consisting of polydimethylsiloxane in which the terminal end of dimethylsiloxane was silylated with dimethylvinylchlorosilane, polydimethylsiloxane in which the terminal end was silylated with dimethylchlorosilane, and a trace amount of platinum catalyst.
Liquid, viscosity 60 cm 4e at 25°C) was dissolved in toluene and the same operation as in Example 3 was carried out. As a result, holes of 1 to 50 μm in the silicon substrate were simultaneously and flatly 5
It was possible to embed it in 102 layers.

(7) Effects of the invention in more detail N5). As explained above, according to the present invention, it is possible to flatten an uneven semiconductor substrate including a groove width of at least 10 μm or more with an insulating layer, and to flatten an insulating layer between wiring layers of a semiconductor device, and to use a thin film magnetic head. , etc. It is used for planarizing the insulating layer between wiring layers in pull memories, etc., and for planarizing the insulating layer in Josephson devices.

[Brief explanation of drawings]

FIGS. 18 to 1B are schematic cross-sectional views for explaining the surface condition by conventional spin coating of resin liquid,
FIG. 2 is a schematic cross-sectional view showing a resin surface according to the present invention, and FIGS. 3A to 3E are schematic cross-sectional views for explaining the case where the present invention is used for isolation between elements of a semiconductor device. . 1... Board, 2... Line, 3a... Resin liquid, 3
b...Impair space, 6...Resin layer after solvent drying using the resin liquid according to the present invention, 11...Silicon substrate, 12...Silicon dioxide (SIO2) layer, 12'
...Silicon dioxide layer embedded in an uneven silicon substrate, 13...A hole with a groove width of 1 μm, 14...
Hole with a groove width of 2 μm, 15... Hole with a groove width of 50 μm, 16.
17...Resin layer. Patent applicant Fujitsu Ltd. Patent agent Akira Aoki Patent attorney Kazuyuki Nishidate (Patent attorney) 1) Yukioben” Akira Yamaguchi Akira 142-kyo

Claims (1)

[Scope of Claims] 1. An insulating layer having a thickness equal to or greater than the depth of the groove is formed on the surface of the uneven substrate having at least one groove having a width of 10 μm or more, and on the insulating layer. In a method for flattening an uneven substrate, the method comprises applying a resin liquid, curing the resin liquid by heating to form a resin layer, and etching to form a flat substrate having an insulating layer in the grooves of the substrate; A method for planarizing an uneven substrate, characterized in that a resin liquid that can be cured at a temperature of 25° C. or higher and exhibits fluidity in a solvent-free state before curing is used as the liquid. 2. The method according to claim 1, wherein the liquid resin is used when the ambient temperature is 25° C. or lower. 3. The method according to claim 1, characterized in that when the ambient temperature exceeds 25°C, a resin having a melting temperature of 40°C or less and a resin concentration of 40% or more is used. 4. The method according to claim 1, characterized in that a resin having a melting temperature exceeding 40°C and a thermosetting temperature higher than the melting temperature by 50°C or more is used. 5 The melting source IW is 50°C or less and the general formula (RlSlO
b) A patent characterized by using a silicone resin represented by n (where R is a monovalent hydrocarbon group, where island is a positive number between 1 and 2, and b is a positive number between 1 and 1.5) The method according to claim 1.