JPS5812340A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To easily smooth the irregularities of a glass film surface comparing when the glass film surface is exposed under oxidizing atmosphere at normal pressure by a method wherein the glass film is exposed under high temperature oxidizing atmosphere under the pressurized condition by previously growing a silicon nitride film under a phosphorus silicic acid glass film. CONSTITUTION:After introducing an N type impurity in a substrate 11 by an ion implantation method, the N type impurity is annealed to form an N type region 15. Next, after forming a silicon nitride film 16 having a film thickness of 500Angstrom by a vapor growth method, a PSG film 17 containing 5% of phosphorus is formed with a film thickness of 1.5mum as a layer insulating film by a vapor growth method. Next, the PSG film 17 is smoothed by applying thermal treatment for 60min under oxygen and hydrogen combustion atmosphere under a pressurized condition of 9kg/cm<2> at 950 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a semiconductor device), and particularly to a method for smoothing a KO film that is easier and more effective than the currently available smoothing heat treatment for a P2O (phosphosilicate glass) film. It relates to a heat treatment method.

During the device manufacturing process, semiconductor devices undergo
An insulating film, a semiconductor layer, or a metal film is formed or selectively removed on one surface, and unevenness is formed on the main surface.If the unevenness is severe, it becomes difficult to process microstructures. Significant manufacturing difficulties arise in the increasingly large metal wiring process.

When a metal interconnection II is applied to a semiconductor element that has a steep step difference during the manufacturing process, the probability that the metal interconnection II will be disconnected at the steep step portion or short-circuited with the ms metal interconnection will increase considerably. As a result, the rate of non-defective products in manufacturing decreases.

Conventionally, in order to smooth out the unevenness, IIcP801[t'' was formed on the uneven structure, and then the glass film was subjected to normal pressure (1 atm) or a pressurized state higher than 1 atm at a high temperature around the softening temperature. There was a method of softening and smoothing in an oxidizing atmosphere.However, depending on the glass No. composition,
When processing under normal pressure, the softening temperature is too high for application to semiconductor manufacturing processes, leading to a major problem of deterioration of device characteristics.Furthermore, when processing under pressure, there is a major problem: ,I! Another advantage is that P8Glif with a low phosphorus concentration can be smoothed at a relatively low temperature when treated in an oxidizing atmosphere containing hydrogen, which has a remarkable smoothing effect. However, the growth effect of the oxide film is strong, and therefore, when there is no film with oxidation-resistant masking properties between the substrate and the PSG film as in the prior art, it is difficult to use the hydrogen-containing atmosphere under pressure. However, if the smoothing heat treatment is not carried out sufficiently, a thick oxide film is formed on the substrate. P
ζ of 2O film.

Smoothing is normally required after high concentration OP-type or N-type impurities have been diffused into the substrate, so if a thick oxide film is formed on the impurity diffusion layer, significant redistribution of impurities may occur. In the pressurized state, it may cause deterioration of device characteristics such as PN junction characteristics such as an increase in leakage current, or cause significant manufacturing difficulties in the process of forming contact holes on the thick oxide film. In particular, it has the disadvantage that smoothing heat treatment cannot be carried out satisfactorily in an atmosphere containing hydrogen.

An object of the present invention is to provide a method for manufacturing a semiconductor device that eliminates such drawbacks and facilitates smoothing of a phosphosilicate glass film.

In smoothing the phosphosilicate glass film of the present invention,
If a silicon nitride film is completely grown under the phosphosilicate glass film in advance, the glass film will be exposed to a pressurized high-temperature oxidizing atmosphere, and the unevenness on the surface of the glass film will be oxidized at normal pressure. smoothed more easily than exposed to a sexual atmosphere,
Moreover, this is based on the knowledge that the silicon nitride M#i formed under the glass film is not oxidized and therefore no oxide film grows on the substrate.

If the present invention is used, the glass film can be subjected to a sufficient smoothing heat treatment, which has the great advantage of facilitating the manufacture of semiconductor devices and increasing reliability.

Next, the invention will be explained with reference to examples. Figure 1 shows invention 1
This is an example applied to smoothing PSGmg on an fI:MO8 semiconductor type device. As shown in FIG. After selective etching and forming gate electrodes and electrical wiring parts, the polycrystalline semiconductor layer is coated with an oxide film 14, and then N-type impurities are added to the substrate 11 (by ion implantation).
After that, a silicon nitride film 16 having a thickness of 500^ is formed by vapor phase epitaxy, and then a phosphorus t-SS film is introduced as an interlayer insulating film. A P8G film 17 containing P8G is grown to a thickness of 15 μm by vapor phase growth. At this time, if the polycrystalline semiconductor layer 13 is processed with high accuracy by the dry etching method, the side surface portion 18t of the semiconductor layer 13
! Usually, the angle is close to perpendicular to the main surface of the base 11, and the side surface 19 corresponding to the side surface 18 of the PSGJ [17] also has an angle close to perpendicular to the main surface of the base 11. Next, after smoothing the P8G film 17 by heat treatment for 60 minutes in an oxygen/hydrogen combustion atmosphere under pressure of 9 kg/cm2 at 950°C, the contact hole 20t- Open the hole, then aluminum wiring 21
If necessary, a protective film is further formed on the aluminum wiring 21 to complete the semiconductor device.

In this example, the smoothing heat treatment of the P2O film was performed at 950°C.
The conditions of extremely strong oxidizing action, such as a pressure of 9 kg/cm and an oxygen-hydrogen combustion atmosphere, were used.

If the conventional structure, that is, the silicon nitride film 16
When a semiconductor element having a structure without 1 is heat-treated, the N-type semiconductor layer 15 has a structure in which, depending on the impurity concentration in the N-type region,
Forms a thick oxide g of 7000λ or more. Furthermore, a similar thick oxide film is formed on the polycrystalline semiconductor layer 13, resulting in deterioration of device characteristics and extreme difficulty in manufacturing, resulting in an extremely low yield rate in manufacturing. However, in this embodiment, since the oxide film does not grow under the nitride film 16, the above-mentioned deterioration of device characteristics and manufacturing difficulties are avoided (sufficient heat treatment for smoothing the P2O film is not required). Can be done.

In this example, Pf9GI117 with a phosphorus content of 5% is used, and the P2O
Smoothening the membrane is extremely difficult. However, since the PSG film 17 is under pressure with extremely strong oxidizing effects, the PSG film 17 is also sufficiently smoothed.

As described above, by using the present invention, even if the PSG film is subjected to smoothing heat treatment in a pressurized oxidizing atmosphere, no new oxide film will grow on the semiconductor substrate.

Therefore, PSGjil, which has a low phosphorus content and has excellent reliability such as moisture resistance, but is difficult to smooth, can be smoothed into a container, which not only increases the reliability of the product.
This method significantly simplifies manufacturing in the contact hole drilling and aluminum wiring processes. This can be expected to have a significant effect on improving performance.

[Brief explanation of drawings]

FIG. 1 is a sectional view for explaining the present invention in detail,
11... P-type substrate, 12... Oxide film,
13... Polycrystalline semiconductor, 14... Oxide film, 15... N-type semiconductor layer, 16...
Nitride film, 17...PEG film, 18...
Side surface of polycrystalline semiconductor layer 13, 19... Side surface of PEG film 17, 20... Contact formation, 21...
...Aluminum wiring.

Claims (1)

[Claims] A step of growing a silicon nitride film on the -1 plane of a semiconductor substrate, a step of growing a silicon oxide film containing yl impurity on the silicon nitride film, and oxidation of the silicon oxide film under a pressure higher than kl atmospheric pressure. Including a process of heat treatment in a sexual atmosphere! #A method for manufacturing semiconductor devices using mold.