JPS63157424A - Manufacture of semiconductor element - Google Patents

Abstract

PURPOSE:To increase the controllability in the case of flattening an insulating film, by a method wherein an end point is exactly detected in the case of etchback to flatten a surface, by monitoring the intensity variation of emission spectrum of nitrogen in plasma luminescence. CONSTITUTION:After an electrode 12 is formed on an Si substrate 11, a silicon oxynitride film with a specified thickness having a refractive index of 1.5 is deposited by a plasma CVD method applying SiH4 and N2O. In the same reaction chamber, a silicon oxynitride film to a specified thickness having a refractive index of 1.8 is deposited by applying SiH4, NK2 and N2O. Then spin coating of a resist or a polyimide resin film 15 is given, and the surface is flatten. Successively, etchback of CF4, CHF2 and He is performed under the condition where the etching speed of the resist, etc., becomes equal to that of a silicon oxynitride film 14. When a silicon oxynitride film 13 begins to appear, an end point detection is performed by monitoring the change of the emission spectrum intensity of nitrogen in a plasma luminescence.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing a semiconductor element having a fine structure, and particularly relates to a method of planarizing an intermediate insulating film used for insulation between wirings. be.

(Prior art) In recent years, due to the miniaturization of semiconductor devices, the spacing between the electrodes that make up semiconductor devices has become narrower, but the thickness of the electrode material has not become much thinner, so the upper layer metal wiring has to be If the metal wiring is wired along a gap, and the covering condition of the metal wiring is poor, the wire may break at the gap, or even if it does not break, the film thickness becomes thinner and the resistance value increases. , wires may break when excessive current is applied due to electromigration. Therefore, it has become important to planarize the intermediate insulating film used for insulating the electrode portion and the metal wiring portion, and for insulating between the uneven gold wiring in the upper layer and the lower layer when multilayer metal wiring is used.

By the way, as for the type of intermediate insulating film, vapor phase growth method (C
Oxide film (PSG film) doped with phosphorus by VD method)
, an oxide film doped with boron and phosphorus (BPSG film), an oxide film doped with arsenic (AsSG film), etc. are used.

Further, FIG. 3 is a manufacturing process cross-sectional view showing an example of a conventional method for manufacturing a semiconductor element.

First, as shown in FIG. 3(a), an oxide film 2 is formed on a silicon semiconductor substrate l, and wiring electrodes 3 are selectively formed thereon.

Next, as shown in FIG. 3(b), as an insulating film,
A silicon nitride film 4 is deposited by plasma CVD.

Next, as shown in FIG. 3(c), the surface of the silicon nitride film 4 is etched and planarized by reactive ion etching.

Next, as shown in FIG. 3(d), the silicon nitride film 4 is densified by heat treatment.

Next, as shown in FIG. 3(e), a wiring layer 5 is formed on the silicon nitride film 4.

Note that as this type of technology, for example, Japanese Patent Application Laid-Open No. 58-31
There is one shown in No. 556.

(Problem to be solved by the invention) However, as mentioned above, PS is used as the intermediate insulating film.
When a G film, a BPSG film, or an As5G film is used, heat treatment must be performed after deposition in order to planarize the film, resulting in a deep diffusion layer. In addition, when flattening an insulating film using the etch bank described above, the flattening rate differs between areas where the uneven peaks are arranged at narrow intervals and wide areas, so it is necessary to etch the insulating film to achieve complete planarization. There are other problems, such as the need to make the film to be banked very thick, and it is difficult to detect the end point of etching.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method for manufacturing a semiconductor element with high reliability, which eliminates the above-mentioned problems and allows flattening of an intermediate insulating film with excellent controllability.

(Means for Solving the Problems) In order to solve the above-mentioned problems, the present invention aims to solve the above-mentioned problems by flattening an insulating film by etching back in a method of manufacturing a semiconductor element. Two types of silicon oxynitride (Silico
After forming a silicon oxy-nitride film and applying a resist or polyimide resin, when etching is performed under conditions where the etch rate of the resist layer and the upper silicon oxynitride film are equal, the underlying silicon oxynitride film may appear. The end point can be detected by capturing the spectra of specific wavelengths observed during plasma emission.

(Function) According to the present invention, two types of silicon oxynitride films having a negative refractive index are successively produced as insulating films by plasma CVD, and then a resist or polyimide resin is spin-coated to flatten the surface. When performing etchback, the nitrogen content differs between the upper and lower silicon oxynitride films, so it is difficult to accurately detect the end point by monitoring changes in the emission spectrum during plasma emission. This makes it possible to improve the controllability when planarizing the insulating film.

(Example) Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a manufacturing process sectional view showing a method for manufacturing a semiconductor device according to the present invention.

First, as shown in FIG. 1(a), after forming an electrode 12 on a Si substrate 11, an intermediate insulating film is formed by plasma CVD.
By the method, 5iHa150scco+ 5NZO3,S
LM, pressure 130Pa, RF150W, temperature 40
A silicon oxynitride film 13 having a refractive index of 1.5 is deposited at a thickness of 60 μm at 0° C. In addition, sccm is standard cubic gloss, and SLM is standard cubic.
It represents 7 minutes per liter, and both indicate the amount that flows per minute.

Next, as shown in FIG. 1(b), in the same reaction tank, 5tHn 150SCCII+, NK33SLM,
NzO500scem, pressure 130Pa, RF150
Silicon oxynitride IIg14 having a refractive index of 1.8 is continuously deposited by 4,000 people at a temperature of 400°C.

Next, as shown in FIG. 1(c), a resist or polyimide resin film 15 is spin-coated to a thickness of 1.6 μm to flatten the surface.

Next, CFtlOOsccm, CHF320sccn
+% tie 400sec.

Under the conditions of RF700W and 300Pa, the resist or polyimide resin film 15 and the silicon oxynitride film 14 are
Etch bank is performed by RIB under the conditions that the etching speed is the same.In this case, the etchback progresses and
As shown in FIG. 1(d), when the silicon oxynitride film 13 begins to appear, the emission spectrum intensity during plasma emission changes due to the nitrogen contained in the wi 13, so the end point can be detected by capturing this change. and finish the etchback.

Next, as shown in FIG. 1(e), a wiring layer 15 is formed on the planarized silicon oxynitride film.

Next, when detecting the end point of etchback, for example, the second
As shown in the figure, the change in intensity of the emission spectrum of 336 nvs is monitored. That is, as shown in this figure, when RF is turned on, the resist or polyimide resin film is etched, the intensity of its emission spectrum increases (a fil region), and when the silicon oxynitride film 14 begins to appear. , the intensity of the emission spectrum further increases bjffJjt), and when the silicon oxynitride film 13 begins to appear, the intensity of the emission spectrum begins to decrease (cti region). Therefore, the RF is turned off and the etch-back is completed.

Note that the present invention is not limited to the above embodiments,
Various modifications are possible based on the spirit of the present invention, and these are not excluded from the scope of the present invention.

(Effects of the Invention) As described above in detail, according to the present invention, two types of silicon oxynitride films having different refractive indexes are successively produced as an insulating film by a plasma CVD method, and a resist or When polyimide resin is spin-coated and etchback is performed to flatten the surface, the nitrogen content differs between the upper and lower silicon oxynitride films, so the emission spectrum of nitrogen during plasma emission changes. By monitoring changes in intensity, the end point can be accurately detected. Therefore, it is possible to improve the controllability when planarizing the insulating film.

In addition, the silicon oxynitride film has both the excellent pansibasing effect of the Si nitride film and the compatibility with the underlying substrate of the Si oxide film, making it possible to provide highly reliable semiconductor devices. .

Further, by forming the wiring layer on the planarized insulating film, it is possible to improve the coverage of the wiring, and the above-described conventional problems can be solved.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of the manufacturing process showing the method for manufacturing a semiconductor device of the present invention, FIG. 2 is a view showing changes in the intensity of the emission spectrum, and FIG. 3 is a cross-sectional view of the manufacturing process showing the conventional method of manufacturing a semiconductor device. It is. 11...Si substrate, 12...electrode, 13...first
14... second silicon oxynitride film, 15... resist or polyimide resin film.

Claims (1)

[Claims] (a) A step of forming a first silicon oxynitride film on an electrode of a semiconductor element; (b) A second silicon oxynitride film having a different refractive index from that of the first silicon oxynitride film. a step of continuously forming an oxynitride film; (c) a step of applying an inorganic film or an organic film and flattening the surface; and (d) a step of forming the second silicon oxynitride film and the inorganic film or Etching the organic film at the same etching rate, detecting a change in emission spectrum intensity due to the appearance of the first silicon oxynitride film due to the etching, and terminating the etching. A method for manufacturing a semiconductor device.