JPS6265427A - Flattening method - Google Patents

Abstract

PURPOSE:To reduce the generation of cracks, and to simplify a process by flattening the surface of a semiconductor device by applying a resin mainly comprising an siloxane group polymer and changing a resin film remaining after etching into SiO2 through oxidation. CONSTITUTION:An SiO2 film 2 in approximately 0.5 thickness is formed onto the surface of a semiconductor device 1 with irregularities or a stepped section in approximately 1mum through a CVD method, a resin mainly comprising an siloxane group polymer is applied in approximately 2.0mu to shape a resin film 5, and the whole is thermally treated for one hr at 200 deg.C in a nitrogen atmosphere. The resin film 5 and the CVDSiO2 film 2 are removed continuously until the thickness of the CVDSiO2 film 2 is reduced to approximately 0.3mum from the upper sections of projecting sections in the semiconductor device 1 through reactive ion etching. Lastly, the remaining resin film 5 is oxidized through heat treatment for one hr at 800 deg.C in an oxygen atmosphere, and properties thereof are changed into a coating 6 turned into SiO2.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for flattening a surface of a semiconductor device having irregularities or steps on the surface in a manufacturing process of a semiconductor device.

(Prior art) Conventionally, in the manufacturing process of large-scale integrated circuits (LSI), K for flattening the glabellar insulating film of multilayer interconnections and the glabellar insulating film of stacked semiconductor devices has been applied using phosphor glass flow, resin insulation method,
Various methods have been used, including resin coating and etching. For example, the 1st Next Generation Industrial Infrastructure Technology Syn4zowam,
In the document "■ Flattening Technique 1" by Kunihiko Takahama published in July 1982, pages 192 to 195 (-), a flattening method using spin-on glass by coating and etching is reported.

The spin-on lath used in the above planarization method is a solution containing silanol (5l(OH)4) as its main component, which is spin-coated onto a semiconductor substrate and then solidified by heat treatment (thus forming an SIO□ film. It is something to do.

An example of this planarization method will be described below with reference to schematic cross-sectional views of the semiconductor device shown in FIGS. 2(a) and 2(b)-(c). In the figure, 1 is a semiconductor device having unevenness or steps, 2
3 is a CvDS102 film, 3 is a spin-on glass film immediately after coating, and 4 is a 5102 spin-on glass film.

First, as shown in FIG. 2(a), a 5in2 film 2 corresponding to an interlayer insulating film is formed on the surface of the semiconductor device 111 having unevenness and steps by CVD method, and then a spin-on lath is applied by spin coating method. The coating film 3 is applied to fill in the unevenness and steps to flatten the surface. Next, as shown in Figure 2(b),
, Coating film 4 obtained by solidifying the cis pin-on glass coating M3 to S10□ by heat treatment for 800' CI time in a nitrogen atmosphere.
Make it. At this time, the thickness of the spin-on glass coating film 3 decreases due to a condensation reaction. Finally, as shown in FIG. 2(c), under etching conditions in which the etching rate of the coated film 4 and the underlying CVD 5in2 film 2 are equal, the film is etched to a desired thickness. Continue to remove by etching.

[Problem that the invention seeks to solve]

The characteristics of the conventional planarization method described above are that spin-on lath is a liquid material that can flatten unevenness and steps on the surface of a semiconductor device by spin coating, and that it is converted into SlO□ by heat treatment. The advantage is that it is possible to leave the coated film of S10□ spin-on glass on the bottle without any adverse effects due to impurity contamination. However, on the other hand, the reaction of converting the spin-on glass coating film into SlO□ is basically due to the condensation reaction of silanol monomers as shown below, and has the disadvantage of a large volumetric shrinkage rate and a tendency to generate cracks.

Further, as mentioned above, since the spin-on lath M is mainly composed of silanol monomer, it is difficult to apply it thickly in one spin coating. For example, in order to flatten a level difference of about 1 μm, there is a method of repeating spin coating about 4 to 5 times. As described above, the above-mentioned conventional planarization method has reliability problems such as easy occurrence of cracks, and requires a large number of steps, so it was considered not to be a suitable method for manufacturing LSIs.

An object of the present invention is to provide a method for planarizing the surface of a semiconductor device that solves the above problems.

(Means for Solving the Problems) The present invention provides a method for planarizing the surface of a semiconductor device having unevenness or steps, in which an insulating film is deposited on the surface of the semiconductor device, and then a silicon-based remer as a main component is deposited on the surface of the semiconductor device. The surface of the semiconductor device is planarized by applying a resin, and then the resin film and the insulating film are etched continuously under etching conditions in which the etching rate of the resin film and the etching rate of the insulating film are equal. and then oxidize the remaining resin film to transform it into a p5io2 film,
A flattened insulating film is formed on the lfN surface of the semiconductor device having irregularities and steps.

The flattening method according to the present invention is characterized by using a resin containing siloxane-based polymer as the main component as a coating material for flattening a semiconductor surface having unevenness or steps and etching it to a desired thickness; The point is that the remaining resin film is oxidized to become SIO□.

Here, the insulating film deposited on the surface of the semiconductor device is CV
It may be a 5in2 film made by the D method, a FiSt, N4 film, a 5102 film made by the Sufu 4 Tsuta method, or an insulating film such as 1jSi, N4 film or nn.

Further, the oxidation of the resin film to 5i02 can be achieved by heat treatment in an oxygen atmosphere, oxygen glaze oxidation, or heat treatment in an ozone atmosphere.

(Function) The siloxane polymer basically forms a two-dimensional polymer as shown in (A) below or a three-dimensional polymer as shown in (B) below.

(A) (B) Here, it corresponds to substituents such as RFiH, OH, CH,, C2H5, and phenyl group. Such a polymer structure can be coated to a thickness of less than 100 ml by one spin coating on a polymer such as silanol.

Further, the shrinkage rate due to heat treatment after coating can also be reduced by selecting substituents. Further, such a siloxane-based polymer can be oxidized and converted into SiO2 by heat treatment in an oxygen atmosphere, oxygen plasma oxidation, or heat treatment in an ozone atmosphere.

(Example) Hereinafter, an example of the planarization method according to the present invention will be described with reference to a schematic cross-sectional view of a semiconductor device shown in FIG. 1(a)Jb)=(c).

In the figure, lii is a semiconductor device having unevenness and steps, 2 is a CV
D5102 film 5 is a resin film whose main component is a siloxane-based polymer, and a resin film whose main component is a siloxane-based polymer converted into 6tiSiO□. First, as shown in FIG. 1 (-), a 0.5 μm thick O5i02 film 2 was formed on the surface of the semiconductor device 1 having 1 μm unevenness and steps using the t-CVT method, and then the above resin was applied using the spin coating method. 2
．． The resin film 5 was completely formed by coating with a thickness of 0 μm, and the resin film 5 was coated for 2 hours in a nitrogen atmosphere.
Heat treatment at 00°C for 1 hour. Here, a siloxane-based polymer gold having a CH group and an OH group as Fi substituents and having a three-dimensional structure is used as the resin. Such a resin can be applied thickly by one spin coating, and also has a small shrinkage rate in a condensation reaction, so it is difficult to cause cracks. Next, Figure 1 (b
), CF and H2 are removed by CVD from above the convex portion of the semiconductor device 1 by reactive ion etching using gas.
Etching is continued until the iO□ film 2 has a thickness of 0.3 μm under etching conditions in which the etching rate of the resin film 5 and the etching rate of the CVD SiO□a2 are equal. The etching conditions at this time are CF
4 and H2 have a flow rate of 100 aecm and 2, respectively.
2IIccm, gas pressure is 80Tf'L Torr,
The high frequency power density is 0.18W/□2. Finally, as shown in FIG. 1(c), the remaining resin film 5 is oxidized by heat treatment at 800° C. for 1 hour in an oxygen atmosphere.
The material was transformed into a cliff cloth film 6 with a size of 10□.

According to the above embodiment, it has the same advantages as the conventional planarization method using spin-on glass sound, and can apply a thickness less than 10 times by spin coating, and can reduce the occurrence of cracks. A flattening method that solved the problem was obtained.

In this example, a resin containing gold as a main component of a siloxane-based polymer with a three-dimensional structure in which CH and OH groups are fully substituted was used as the resin to be coated, but other resins containing siloxane-based polymer as a main component may also be used. But it is possible. In addition, if the combination of the distribution film and the insulating film deposited on the semiconductor substrate is changed, it is possible that the same etching speed cannot be obtained under the etching conditions described in the examples. By selecting the type of gas, flow rate, etc., it is possible to perform FJt to obtain a uniform etching speed.

〔Effect of the invention〕

As described above, according to the present invention, a method for planarizing the surface of a semiconductor device can be obtained which is significantly improved in that the generation of cracks is reduced and the process is simple compared to the conventional method for planarizing the surface of a semiconductor device.

Therefore, according to the present invention, it is possible to provide a planarization method that is highly reliable and has simple steps, and has the effect that it can be widely used in various processes that require planarization in the LSI manufacturing process.

[Brief explanation of drawings]

FIGS. 1(a), (b), and (e) are schematic cross-sectional views showing one embodiment of the creation process of the method for planarizing the surface of a semiconductor device according to the present invention, and FIGS. 2(a), (b) , (c) are schematic cross-sectional views showing manufacturing steps of a conventional method for flattening the surface of a semiconductor device. 1... Semiconductor device having unevenness or steps, 2... CV
D510□ film, 5... Resin film containing siloxane-based polymer as main component of gold, 6... Resin film containing 5102 siloxane-based polymer as main component.

Claims (1)

[Claims] In a method for planarizing a surface of a semiconductor device having unevenness or steps, the surface of the semiconductor device is planarized by depositing an insulating film on the surface of the semiconductor device, applying a resin containing a siloxane-based polymer as a main component, and then flattening the surface of the semiconductor device. Under etching conditions in which the etching rate of the resin film and the insulating film are equal, the resin film and the insulating film are continuously removed by etching, and the remaining resin film is oxidized to transform into a SiO_2 film. A planarization method comprising forming a planarized insulating film on the surface of the semiconductor device having unevenness or steps.