JPS61248437A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To improve reliability and integration degree by a method wherein an insulation film is formed on a part where a field region is etched by a coating method. CONSTITUTION:After an oxide film 2 is formed on a substrate 1, photoresist is applied and the photoresist film 4 is left only on a region where elements are to be formed. Then, utilizing the film 4 as a mask, the oxide film 2 and the substrate 1 are etched to the predetermined depth. After the film 4 is removed, the surface is coated with an impurity diffusion source solution containing boron for prevention of a field inversion to form a thin impurity diffusion source film 3. Then an insulation film forming solution is applied thick so as to cover over the whole surface of the substrate 1 and baked to form a smooth insulation film 5 and then the insulation film 5 and the oxide film 2 are etched as far as the region where the elements are to be formed is exposed. With this constitution, leakage defects can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for forming a semiconductor device, and more particularly to a method for forming an element isolation film with a flat surface.

[Conventional technology]

As semiconductor devices become more highly integrated, surface smoothing to eliminate unevenness in element regions and field regions has become a major issue in order to prevent wiring breaks and realize multilayer wiring structures. The conventional smoothing method is to cover the entire area intended for the bottom of the element shape with nitridation, thermally oxidize the field area, remove gold from this oxide film, and then thermally oxidize again. In addition, a method is used in which a nitride film is grown before reoxidation, and the nitride film is left on the walls of all the regions where elements are to be formed, and then oxidized, and a method is used in which boron is diffused before reoxidation to prevent field reversal. was.

[Problems that the invention helps solve]

However, unlike this type of smoothing method, 1) the number of steps is large, (2) a bird's beak occurs in the thermal oxidation method and the dimensional accuracy of the element deteriorates, and (3) thermal oxidation (usually 10
(4) The boron diffusion layer of the field inversion prevention layer is heated to a depth of 19 degrees and The main drawback is that the lateral spread is difficult to control.

It is an object of the present invention to eliminate the above-mentioned drawbacks, to realize a very simple surface smoothing between the element region and the field region, and to achieve a semiconductor device that enables high integration of semiconductor devices without causing characteristic deterioration. The purpose is to provide a manufacturing method for.

[Means to completely solve skin problems]

The method for manufacturing a semiconductor device of the present invention includes the steps of forming an entire oxide film on a semiconductor substrate,
? ! - a step of etching the surface of the semiconductor substrate other than the element forming area to a predetermined depth; and a step of applying an impurity diffusion source liquid to the entire surface, and then applying an insulating film shaping liquid and baking it to form an insulating film. A step of etching the oxide film and the insulating film to expose the entire surface of the semiconductor substrate in the bottom region of the element shape.

〔Example〕

Next, an embodiment of the present invention will be described with reference to the drawings.

FIGS. 1(a) to 1(e) are process cross-sectional views for fully explaining one embodiment of the present invention, and show a case where the present invention is applied to a 9M08 type semiconductor device.

First, as shown in FIG. 1(a), a P-type silicon substrate 1
An oxide film of several hundred amperes is formed on the surface by thermal oxidation.
It has an e-shaped bottom. This oxide film 2 is used as a mask for an impurity diffusion source solution used to prevent field inversion in the next step. After the oxidized A2 is completely released, photoresist is applied to leave the photoresist film 4 only in the area where the element is to be formed. Next, as shown in FIG. 1(b), using a photoresist Ml mask, the oxide a2 in the field region and the silicon substrate 1 are etched to a predetermined depth by reactive ion etching. Next, as shown in FIG. 1(C), after removing the photoresist film 4t'', a thin layer of an impurity diffusion source solution containing boron is applied to the surface to prevent field reversal to form an impurity diffusion mark.Next, the first factor ( As shown in the figure, apply the insulating film forming liquid (alcoholic solution of silicon compound containing no impurities) thickly to the entire surface of the silicon substrate and bake at 200 to 300°C.This operation may be performed as necessary. Five insulating films with a smooth surface are formed.Next, as shown in FIG. Membrane 2 is etched.

After forming the element isolation insulator wj#, 5t, the element is formed through processes such as total oxidation, photoetching, diffusion, and vapor deposition in the area where the element is to be formed.

As described above, according to the embodiments of the present invention, the semiconductor surface can be smoothed through a much simpler process than in the past, and the dimensions of the element area are determined by the dimensions of the initial photoresist mask, making it easier to design. Characteristic values close to the values can be obtained. Further, crystal defects are less likely to occur inside the semiconductor substrate, which does not require high-temperature oxidation, and leakage defects caused by defects can be reduced.

〔Effect of the invention〕

As described above in detail, nine aspects of the invention are in accordance with the present invention.

The field area is etched and an insulating film is formed on this part by a coating method. The effect is great because it provides a method for manufacturing a semiconductor device that is smooth, highly reliable, and has an improved degree of integration.

[Brief explanation of drawings]

1A to 1E are cross-sectional views of certain steps to explain the implementation of the present invention. 1... PM silicon substrate, 2... Oxide film, 3...
Impurity diffusion source film, 4... photoresist film, 5... insulating film.

Claims (1)

[Claims] A step of forming an oxide film on a semiconductor substrate, a step of removing the oxide film in areas other than the element formation region, a step of etching the surface of the semiconductor substrate other than the element formation region to a predetermined depth, and a step of diffusing impurities over the entire surface. The method includes a step of applying a source solution and then applying an insulating film forming liquid and baking it to form an insulating film, and a step of etching the oxide film and the insulating film to expose the surface of the semiconductor substrate in the element formation region. A method for manufacturing a semiconductor device, characterized in that: