JPS6138852B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a chemical vapor deposition method for insulating films in the manufacture of semiconductor devices.

For example, in the manufacture of semiconductor devices such as integrated circuits, an insulating film is deposited on a metal wiring layer formed on a semiconductor substrate on which element formation has been completed, and an upper layer of metal wiring is further formed on the insulating film. There is a wiring process.

However, when forming an insulating film in the multilayer wiring process, silane (SiH ₄ Alternatively, an insulating film such as silicon dioxide (SiO ₂ ) or phosphosilicate glass (PSG) is grown by chemical vapor deposition (CVD) using silane + phosphorus (SiH ₄ + PH ₃ ). ing.

However, in this CVD method, the substrate to be grown is exposed to a high temperature of about 400 to 500°C for about 10 to 20 minutes, so the Al and Al/Si in the lower wiring layer formed on the substrate to be grown are Recrystallization occurs, and the crystal grains become coarser over time, resulting in the formation of protrusions and whiskers on the metal wiring layer.

Conventionally, insulating films of SiO ₂ or PSG were deposited under the conditions described above, resulting in protrusions and whiskers protruding onto the insulating film, cracks and pinholes in the insulating film, and damage to the insulating film. There have been problems such as insulation deterioration between the upper layer metal wiring deposited on the film and the metal wiring below the insulating film, and disconnection of the upper layer metal wiring.

In view of the above problems, the present invention provides a chemical vapor deposition (CVD) method that does not generate protrusions or whiskers in the underlying metal wiring layer.

That is, in the manufacture of semiconductor devices, when an insulating film is formed by chemical vapor deposition on a metal wiring layer formed on a semiconductor substrate, the metal wiring layer is previously exposed to electrons prior to the formation of the insulating film. The method is characterized in that the heat treatment is performed using a beam at a temperature higher than the vapor phase growth temperature of the insulating film.

The present invention will be explained in detail below with reference to illustrated embodiments.

1 to 4 are process explanatory diagrams of an embodiment of the present invention.

According to the present invention, for example, in the production of semiconductor integrated circuits, etc., the method of the present invention first uses SiO ₂ to cover the surface of a Si substrate 1 on which element formation has been completed, as shown in FIG.
An electrode window 3 is formed on the membrane 2 to a thickness of 1 to 1.5 [μ
m] of Al is the lower metal wiring layer 4 made of Al/Si.
to form.

Next, as shown in FIG. 2, the Si substrate 1 is placed on the anode 5 of an electron beam exposure device, and an energy density of 10 ⁶ to 10 ⁷ [W/cm] is applied to the metal wiring layer 4 of the substrate. The surface layer of the metal wiring layer 4 is irradiated with an electron beam 6 for a very short period of time of about 10 ^-7 [sec], and the surface layer of the metal wiring layer 4 is
Heat treatment (annealing) is performed by raising the temperature to approximately 500℃. As a result, as shown in FIG. 3, a thin Al or Al/Si recrystallization 7 of about 500 Å is formed on the surface layer of the metal wiring layer 4.

However, since the annealing is performed for a very short time, the recrystallized grains of Al or Al/Si formed are very fine. Therefore, even if heat treatment is performed after this step, no protrusions or whiskers will be generated in the metal wiring layer.

Next, the Si substrate 1 is treated with SiH ₄ in a low pressure CVD equipment.
Heat at about 450℃ for about 10 minutes while flowing PH ₃ ,
As shown in FIG. 4, an insulating film 8 made of PSG is deposited to a thickness of about 1 [μm] on the SiO ₂ film 2 on the surface of the Si substrate 1 and the recrystallized layer 7 of the metal wiring layer 4.

However, since the annealing temperature of the metal wiring layer by the electron beam is set higher than the temperature of the vapor phase growth, recrystallization of the metal wiring layer does not proceed during the vapor phase growth, and therefore large protrusions and A uniform insulating film can be deposited on a metal wiring layer without whiskers.

The above electron beam annealing method (1) does not depend on the crystal structure of the metal, (2) can create a desired beam area, and (3) can control the annealing depth by changing the acceleration energy given to the electrons.
(4) Instantaneous annealing is possible by pulse irradiation.
As it has many advantages such as, it is possible to form an annealed layer of desired depth on various metals, and annealing can control crystal grains and promote uniformity of structure in mixed metals. You can also do this.

Therefore, the method of the present invention is not limited to the above-mentioned embodiments, but can also be applied to SiO ₂ , PSG, silicon nitride (Si ₃ N ₄ ), etc. by chemical vapor deposition on wiring layers made of various metals or alloys other than those mentioned above. Of course, this method can also be applied when depositing an insulating film.

As explained above, according to the method of the present invention, when an insulating film is deposited on a metal wiring layer by chemical vapor deposition, it is possible to prevent protrusions and whiskers from occurring due to recrystallization of the metal wiring layer. This eliminates the occurrence of penetration, cracks, pinholes, etc. in the recrystallized metal, and is extremely effective in improving the manufacturing yield and reliability of semiconductor devices such as integrated circuits.

[Brief explanation of the drawing]

1 to 4 are cross-sectional views showing the steps of an embodiment of the present invention. In the figure, 1 is a silicon (Si) substrate, 2 is a silicon dioxide (SiO ₂ ) film, 3 is an electrode window, 4 is a lower metal wiring layer, 5 is an anode of an electron beam exposure device, and 6 is an anode of an electron beam exposure device.
7 is an electron beam, 7 is a recrystallized layer, and 8 is an insulating film.

Claims (1)

[Claims] 1. When forming an insulating film by chemical vapor deposition on a metal wiring layer formed on a semiconductor substrate, prior to forming the insulating film, the metal wiring layer is heated with an electron beam to a temperature lower than the vapor growth temperature of the insulating film. A method for manufacturing a semiconductor device, comprising a step of heat treatment at a high temperature.