KR960000367B1 - Metalizing method of semiconductor device - Google Patents

Abstract

forming insulating film having a contact part on a semiconductor substrate; forming the first metal layer on a lower film exposed to the inner contact part and the contact at a temperature of less than two hundred centigrades; forming a metal plug in th contact part by fusing the first metal layer; forming the second metal layer at front side of the semiconductor substrate where the metal plug is formed; heat processing the second metal layer.

Description

Wiring layer formation method of semiconductor device

1 is a cross-sectional view showing a metal wiring layer manufactured by a pre- filed method.

2 to 9 are process flowcharts showing one embodiment of a method for forming a metal wiring layer according to the present invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a semiconductor device, and more particularly, to a method for forming a wiring layer of a semiconductor device having large topography.

As semiconductor devices become more highly integrated, semiconductor wiring methods occupy the most important positions in the semiconductor manufacturing process because they are factors that determine the speed performance, yield, and reliability of semiconductor devices. Conventionally, when applying a relatively small outer surface shape such as a contact hole having a low aspect ratio (a ratio of depth to width) or a low depth step, application of metal step coverage is not a problem. However, as the degree of integration of the semiconductor device increases, the contact holes are considerably smaller and the regions coated with impurities formed on the surface of the semiconductor substrate are much thinner. Conventional aluminum wiring processes have suffered from reliability failure of aluminum interconnect due to high aspect ratio of contact holes and poor step coverage of sputtered aluminum, increased contact resistance due to silicon precipitates and aluminum spikes. As a result, many problems such as deterioration of shallow bonding characteristics are included, and therefore, there is a need to improve the semiconductor device for high speed performance, high yield, and good reliability despite the high aspect ratio of the contact hole and the large depth of the step.

Therefore, new methods have been proposed to overcome the above problems of the conventional wiring process. For example, the following method is known in order to prevent the deterioration of the reliability of the semiconductor device due to the failure of aluminum connection due to the high aspect ratio in the aluminum wiring process and the poor step coverage of sputtered aluminum.

In Japanese Patent Laid-Open No. 62-132348 (Yukiyasu Sugano et al.), A metal wiring layer is formed on a step on a semiconductor substrate to improve the shape of a film against irregular steps of a semiconductor device, and then the wiring layer is heated and melted to be flattened. The method of making is described.

In Japanese Patent Laid-Open No. 63-99549 (Shin Fair Iijima et al.), A metal wiring layer is formed on a semiconductor substrate with contact holes and steps to improve the reliability of the wiring and to enable mutual contact between the multilayers. And a method of heat melting the same. The publication includes forming a plurality of devices on a semiconductor substrate, depositing an insulating film on a substrate including the device, forming a contact hole in the insulating film to reach a predetermined position of the device, and forming the contact hole and the insulating film. A titanium nitride film was formed on the surface, a metal wiring layer was deposited on the entire surface of the titanium nitride film, and the metal layer was heated and melted to flatten the surface of the metal layer, and then the metal layer and the titanium nitride film were formed in accordance with a predetermined wiring pattern. A method of manufacturing a semiconductor device is described in which a metal wiring layer is formed on a semiconductor substrate comprising etching to form at least a first layer wiring layer to form mutual contact between the multilayers.

In Japanese Patent Laid-Open No. 62-109341 (Masahiro Shimizu et al.), In order to improve the reliability of a semiconductor device due to wiring failure, when coating the electrode or the wiring film to form a good coating property such as contact with the surface of the insulating film surface A method of forming an aluminum conductive film, such as an aluminum alloy film, is proposed. According to Masahiro Shimizu et al., There is provided a method for manufacturing a semiconductor device comprising applying a liquid aluminum compound or a solution containing aluminum onto a silicon substrate and then heat treatment to form an aluminum conductive film.

According to the above-described method, aluminum or an aluminum alloy is melted and reflowed to fill a contact hole. Since all of the above publications include a reflow method in which aluminum or an aluminum alloy is melted, the semiconductor wafer manufactured by this technique should be positioned horizontally so that the flowing molten material fills the contact holes. In addition, the shrinkage of the metal occurs in the insulation area due to temperature changes. That is, the fluidized metal layer liquefied by heating the metal layer above the melting point of aluminum or aluminum alloy fills the contact hole. The liquid metal layer will attempt to reduce the surface tension, and thus, upon solidification, the liquid metal layer will contract or twist to expose the bottom semiconductor material. Moreover, it is difficult to obtain the same result because the heat treatment temperature cannot be adjusted accurately. In addition, according to the above method, even if the contact hole can be buried, the remaining portion of the metal film becomes rough so that subsequent photographic processes cannot be performed. Therefore, a secondary metal forming process may be needed.

In addition, a method of forming a barrier layer in a contact hole formed on a semiconductor substrate in order to prevent deterioration of a shallow junction region due to aluminum spikes and to improve reliability of a semiconductor device is known. For example, US Pat. No. 4,897,709 describes a semiconductor device that further includes a titanium nitride film as a barrier layer in a contact hole to prevent reaction between the wiring and the semiconductor substrate. The titanium nitride film can be formed by using a low temperature CVD apparatus and by a low pressure CVD method, and has an excellent property of having good step coatability in a fairly fine contact hole having a high aspect ratio. After the titanium nitride film is formed, a wiring layer is formed by a sputtering method using an aluminum alloy.

In addition to the above, instead of melting aluminum or an aluminum alloy, US Pat. No. 4,970,176 (Drayy et al.) Describes a multi-step metallization method in order to improve the step coverage of the metal.

According to one of the above patents, after depositing a thick metal layer of a predetermined thickness on a semiconductor wafer at a low temperature, the temperature is raised to a high temperature (about 400 ° C to 500 ° C) so that the metal reflows, and the rest of the metal layer of the predetermined thickness is deposited. After depositing the first metal layer, the second metal layer is deposited while the temperature is raised to a high temperature such that the metal reflows. Reflow of the metal layer occurs through particle growth, recrystallization and bulk diffusion.

On the other hand, it is reported that the liquidity of aluminum-silicon suddenly increases when the semiconductor substrates of Ono et al. Are kept above 500 ° C (Hisako Ono, et al., In Proc., 1990 VMIC Conference June 11-12, pp. Ono et al. Teach that the stress of aluminum-1% silicon film changes rapidly at 500 ° C., and stress relaxation of the aluminum-1% silicon film occurs abruptly at this temperature. It also teaches that the substrate temperature should be maintained at 500 ° C to 550 ° C in order to fill the contact holes satisfactorily.

The above phenomenon is caused by a mechanism different from the reflow phenomenon of the metal layer in the methods such as Tracy.

The inventors deposit the metal at a low temperature (200 ° C. or less) using the movement phenomenon of the metal atoms by stress relaxation of the metal layer, and then deposit the metal at a temperature of 80% of the metal melting point to the metal melting point. A post-treatment method was invented to completely fill a contact hole in a semiconductor device (name of the invention: a method for forming a metal wiring layer) and filed a patent application on June 18, 1990 (Patent Application No. 90-10027).

However, even in the above-described prior art, voids as shown in FIG. 1 are generated at a high step in which the aspect ratio of the contact hole becomes 1.5 or more. That is, the shadowing effect is increased due to the high aspect ratio of the contact hole, and the increase of the shadowing effect prevents the sputtered aluminum atoms from forming a continuous aluminum film on the sidewalls of the contact hole due to the increase of the shadowing effect. Even if the aluminum atoms move to the bottom of the contact hole and are not sufficiently buried, the accumulation of aluminum atoms around the contact hole inlet causes clogging or narrowing of the inlet of the contact hole. Only flattened.

Accordingly, an object of the present invention relates to a metal wiring layer forming method capable of forming a highly reliable wiring by filling the contact hole irrespective of the aspect ratio of the contact hole in order to solve the problems of the prior art as described above.

In order to achieve the above object, the method of the present invention comprises the steps of forming an insulating film having a contact hole on a semiconductor substrate; Forming a primary metal layer only on the inner surface of the contact hole and on the underlying film exposed to the contact hole at a temperature of 200 ° C. or lower; Melting the primary metal layer to form a metal plug in the contact hole; Forming a secondary metal layer on an entire surface of the semiconductor substrate on which the metal plug is formed; And a step of heat-treating the secondary metal layer.

Hereinafter, with reference to the accompanying drawings will be described the present invention.

2 to 9 is a siege sequence showing an embodiment of a method for forming a metal wiring layer according to the present invention, which is an improvement of the patent. In this embodiment, an impurity injection region is used as the lower wiring layer as an example.

FIG. 2 illustrates a process of forming the lower wiring layer 11, the barrier layer 15, and the primary metal layer 17. First, the impurity implantation region of the second conductive type is formed in the semiconductor substrate 10 of the first conductive type. A lower wiring layer 11 is formed, and an interlayer insulating film 13 is formed on the entire surface of the resultant. Subsequently, by applying a mask pattern on the interlayer insulating film, the interlayer insulating film is etched even when the lower wiring layer is exposed, thereby forming contact holes, and removing organic substances remaining on the substrate surface and natural oxide film present on the bottom surface of the substrate in the contact hole. After the cleaning, the barrier layer 15, for example titanium nitride (TiN), is physically or chemically deposited on the entire surface of the resultant, and the primary metal layer 17, for example, an aluminum film is heated on the barrier layer 15 at a temperature of 200 ° C. or lower. Physically deposit in At this time, the thickness of the aluminum film which is the primary metal layer is 1/2 of the inlet size of the contact hole. Here, the aluminum film may be an aluminum film containing silicon, copper, or titanium instead of a pure aluminum film.

FIG. 3 shows the process of forming the polymer 19. After the process of FIG. 2, the polymer 19 having the same viscosity as the photoresist is applied to the entire surface of the resultant product by spin coating. As shown in the figure, the empty space in the contact hole is buried and then a bake process is performed.

4 is anisotropically etched to the entire surface of the resultant polymer filled in the contact hole, but slightly dry than the thickness of the primary metal layer to etch the primary metal layer 17 'and the polymer 19' in the contact hole. Represents the process of removing all but leaving only.

5 illustrates the removal of the polymer, in which the polymer remaining only in the contact hole is first removed by ashing, and the exposed primary metal layer 17 'and the barrier layer 15 are corroded. After submersion in the polymer removal solution, such as PRS-2000, R-10 solution, to completely remove the residual polymer, and then rinse with pure water (DI water).

FIG. 6 shows a process of instantaneously melting the aluminum film, which is the primary metal layer, at a high temperature after the process of FIG. 5 to form an aluminum plug plug 17 ″. In this case, the contact hole is almost buried or the aspect ratio of the contact hole is alleviated, and the degree of embedding of the aluminum plug may be made by adjusting the amount of aluminum remaining in the etching process of FIG. 4.

FIG. 7 illustrates a process of forming the secondary metal layer 21. When the secondary metal layer 21, for example, an aluminum film of 3000 의 or less is continuously deposited at low temperature without atmospheric exposure or is subjected to atmospheric exposure after the process of FIG. After the sputter cleaning (sputter cleaning) prior to the formation of the secondary metal layer is deposited without atmospheric exposure to form a secondary metal layer through a process. Here, the aluminum film may be an aluminum film containing silicon, copper, or titanium instead of a pure aluminum film.

FIG. 8 illustrates the process of embedding the contact hole. When the substrate obtained by the process of FIG. 7 is moved to another sputtering reaction chamber without exposure to air, and then heat treated at 450 ° C. or more for several minutes, atoms of the aluminum film deposited at low temperature are Grain grows as the movement of the particles occurs actively, and investment occurs on the primary metal layer plug (reference 17 ″ in FIG. 7). Reference numeral 21 'represents a state after the heat treatment of the secondary metal layer.

FIG. 9 shows the process of forming the tertiary metal layer 23. After the process of FIG. 8, the remaining thickness of the total wiring thickness is deposited to form the tertiary metal layer 23, for example, an aluminum film, thereby completing the fabrication of the metal wiring layer. . Subsequently, the aluminum film may be an aluminum film containing silicon, copper, titanium, or the like instead of the pure aluminum film. In this case, if the secondary metal layer 21 and the tertiary metal layer 23 formed in the process of FIG. 8 use an aluminum film containing impurities (silicon, copper, or titanium) instead of the pure aluminum film, the impurities The deposition may be carried out at different concentrations.

As described above, in the method for forming a metal wiring layer according to the present invention, after the aluminum plug is formed in one piece, another aluminum film is deposited on the aluminum plug and subjected to heat treatment, whereby the inside of the contact hole can be completely buried only with the aluminum film. That is, the inside of the contact hole having an aspect ratio of 1.5 or more can be completely buried only with the aluminum film without the formation of aluminum disconnection and voids caused by the shading effect, thereby improving the reliability of the metal wiring layer.

Claims (10)

Forming an insulating film having a contact hole on the semiconductor substrate; Forming a primary metal layer at a temperature of 200 ° C. or lower only on the underlayer exposed to the contact hole when the contact flows; Melting the primary metal layer to form a metal plug in the contact hole; Forming a secondary metal layer on an entire surface of the semiconductor substrate on which the metal plug is formed; And heat-treating the secondary metal layer. The method of claim 1, further comprising depositing a tertiary metal layer on the heat treated secondary metal layer. The method for forming a wiring layer of a semiconductor device according to claim 1, further comprising the step of forming a barrier layer before forming the primary metal layer. 4. The method for forming a wiring layer of a semiconductor device according to claim 3, wherein said barrier layer is titanium nitride. The method for forming a wiring layer of a semiconductor device according to claim 1 or 2, wherein the primary, secondary and tertiary metal layers are pure aluminum films or aluminum films containing impurities. 6. The method for forming a wiring layer of a semiconductor device according to claim 5, wherein said impurity is silicon, copper, or titanium. The method for forming a wiring layer of a semiconductor device according to claim 1, wherein the step of melting the primary metal layer to form a metal plug in the contact hole is performed by instantaneous melting of the primary metal layer at a high temperature. The method of claim 5, wherein the secondary metal layer is continuously deposited at a low temperature of 3000 kPa or less without atmospheric exposure, or, if the atmospheric exposure is high, after the sputter cleaning before the formation of the secondary metal layer, the low temperature to 3000 kPa or less. Method for forming a wiring layer of a semiconductor device, characterized in that deposited in. The method of forming a wiring layer of a semiconductor device according to claim 8, wherein the heat treatment step of the secondary metal layer is performed for several minutes at 450 占 폚 or more after moving to another sputtering reaction chamber without exposure to the atmosphere after formation of the secondary metal layer. . 6. The method of forming a wiring layer of a semiconductor device according to claim 5, wherein when the aluminum film containing impurities is contained in the secondary metal layer and the tertiary metal layer, the impurity concentration is different.