JPS62104165A - Semiconductor device - Google Patents

Abstract

PURPOSE:To take out highly reliable electrodes even from minute contact holes, by providing a barrier layer at the bottom part of each contact hole, which is provided in an insulating film formed on a semiconductor substrate, and fusing and burying Al alloy in the contact hole. CONSTITUTION:On an Si substrate 11, and SiO2 film 12 is formed. Contact holes 13 are selectively formed. A TiN film 14 as a barrier layer and a 30% Mg-Al alloy film 15 are sequentially deposited. The Mg-Al alloy film 15 and the TiN film 14 are patterned so that the films remain only in and around the contact holes 13. Thus an Mg-Al alloy pattern 16 and a TiN pattern 17 are formed. When, the Si substrate undergoes heat treatment at 510 deg.C, the Mg-Al alloy pattern 16 is fused, and the contact holes 13 are buried with an Mg-Al alloy body 18. Then, a Tin film 19 is deposited on the SiO2 film 12 including the Mg-Al alloy body 18. Thereafter, an Al film is deposited on the entire surface of the film 19. Patterning is performed, and an Al wiring 20 is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor device, and particularly to a semiconductor device in which electrodes can be reliably extracted through a minute contact hole.

[Technical background of the invention]

In semiconductor devices, electrodes are taken out through contact holes. Conventionally, to take out such an electrode, an aluminum film with a contact hole formed therein has been formed, and the aluminum film has been used as a wiring and at the same time as an electrode lead out.

[Problems with background technology]

Incidentally, as the density of semiconductor devices increases, the contact holes are also reduced in size, but the depth of the contact holes remains approximately constant. For this reason, there is a problem in that the aluminum film is difficult to be deposited inside the contact hole, and the deposition rate (step force balayage) particularly on the side wall of the contact hole is deteriorated.

This will be explained in detail with reference to FIG.

1 in the figure is a silicon substrate, and silicon oxide lI2 is formed on this substrate 1. This oxide film 2 has contact holes 3a, 3b, . . . formed therein. The contact hole 3a has a size of 4 μm×4 μm, and the contact hole 3b has a size of 1 μm×1 μm. The silicon oxide film 2 having the contact holes 3a and 3b with different opening sizes is coated with a sputtering technique to form a 1-thick film.
When an aluminum film 4 of μm thickness is deposited, the step force burrage of the aluminum film 4 is good at 80% or more in the contact hole 3a with a large opening size, but it is less than 10% in the contact hole 3b with a small opening size.

As a result, the reliability of taking out the electrode through the contact hole 3b is significantly reduced.

[Purpose of the invention]

The present invention aims to provide a semiconductor device having a structure in which highly reliable electrodes can be taken out even through minute contact holes.

[Summary of the invention]

The present invention includes an insulating film provided on a semiconductor substrate, a contact hole formed in the insulating film, a barrier layer provided at least at the bottom of the contact hole, and a barrier layer embedded in the contact hole by melting. The invention is characterized by comprising an aluminum alloy made of aluminum alloy. According to the present invention, as described above, it is possible to obtain a semiconductor device having a structure in which highly reliable electrodes can be taken out even through a minute contact hole.

As the barrier layer, a nitride of a high melting point metal or the like can be used, and TiN is particularly suitable.

As the aluminum alloy, an AR gold alloy containing MQ, which can be melted at a much lower temperature than pure aluminum, is suitable. In this An-Ma gold alloy, the melting temperature is the lowest (approximately 450°C) at 35% by weight, which is a range that does not have any adverse effects on electrode extraction such as resistance due to the MO contained. It is preferable to use a △2 alloy with an Mg content of less than 2%.
The range is preferably from 0% by weight (melting temperature about 550°C) to 35% by weight.

[Embodiments of the invention]

Hereinafter, embodiments of the present invention will be described in detail together with manufacturing steps shown in the drawings.

Example 1 First, a silicon oxide film 12 with a thickness of about 1 μm is formed on a silicon substrate 11 on which a semiconductor element (not shown) is formed, and then a silicon oxide film 12 with an opening size of, for example, 1 μm×1 μm is formed in the oxide film 1112.
A contact hole 13 of m in diameter was selectively formed by photoetching technology.

Next, a TiNl barrier layer with a thickness of approximately 1000 nm is formed on the silicon oxide film 12 including the contact hole 13.
After depositing 114, a 30% Mg-2 alloy film 15 is deposited on the entire surface by sputtering to a thickness of 8,000 mm (as shown in FIG. 1(a)). The melting point of this 30% MO-A°C alloy is 500°C.

Next, the MO-AR alloy film 15 and the TiN film 14 are
The MO-AR alloy pattern 16 and T are patterned so that they remain only in the contact hole 13 and its surroundings.
An iN pattern 17 was formed (as shown in FIG. 3(b)). Subsequently, the silicon substrate 11 was heat-treated at 510° C., which is slightly higher than the melting point of the MO-AJ2 alloy. At this time, Mg-Afi
The alloy pattern 16 was melted, and the contact hole 13 was filled with the MO-AQ alloy body 18 by subsequent cooling (
Figure (C) shown). Furthermore, since the TiN pattern 17 is formed on the inner surface of the contact hole 13, 30%
Mg-A/! When the alloy pattern 16 is melted, the reaction between the A° C. and the silicon substrate 11 is prevented, and the occurrence of A2 protrusions, etc. on the surface of the substrate 11 under the contact hole 13 is prevented.

Next, the silicon oxide film 1 containing the MO-AR alloy body 18 is
2 again by sputtering to a thickness of 1000 mm
After depositing Nl 119, a 1 μm thick film is deposited on the entire surface by sputtering, and patterned to form a λ wiring 20 (as shown in FIG. 2D).

As shown in FIG. 1(d), the semiconductor device of the present invention includes a silicon oxide film 12 provided on a silicon substrate 11, and a minute contact hole 13 formed in this oxide film 12.
A TiN pattern 17 as a barrier layer provided at least at the bottom of the contact hole 13, and an MCI-
Aλ alloy body 18 and this MO-A alloy body 18 are coated with TiN.
It is composed of an A2 wiring 2o connected via a wire 19.

Therefore, the MO-Ag alloy body 18 formed by melting is embedded in the minute contact hole 13, and this MQ-
A2 arrangement with a semiconductor element (not shown) on the substrate surface via the Ag alloy body 18! 20, it is possible to prevent breakage at the side wall of the contact hole, which is caused by the miniaturization of the contact hole as in the prior art. Moreover, a low resistance TiN pattern (barrier layer) is provided at the bottom of the contact hole 13.
17 is provided, and M is provided throughout the contact hole 13.
Since the g-A42 alloy body 18 is embedded, the H2 wiring 20 can be connected with low resistance to a semiconductor element (not shown) on the silicon substrate.

In addition, the MC embedded in the contact hole 13 by melting
Since the J-A4 alloy body 18 is made of pure aluminum, the M
The thermal influence on the semiconductor element formed on the substrate 11 during melting of the O-A°C alloy can be significantly reduced.

Furthermore, since the TiN pattern 17, which is stable and has a low resistance at the temperature at which the MO-Ag alloy is melted, is provided as a barrier layer at least at the bottom of the contact hole 13, the Ag and the substrate will be separated when the MO-Ag alloy is melted. 11
reaction with silicon, Ag grammar, etc. can be prevented.

Example 2 First, silicon oxide 1112 with a thickness of about 1 μm is formed on a silicon substrate 11 on which a semiconductor element (not shown) is formed, and then a silicon oxide film 1112 with an opening size of, for example, 1 μm×1 μm is formed in the oxide film 12.
A contact hole 13 of m in diameter was selectively formed by photoetching technology.

Subsequently, by depositing tungsten using low pressure CVD technology, a W film 21 as a barrier layer with a thickness of approximately 1000 mm is formed only at the bottom of the contact hole 13, and then a W film 21 with a diameter of 0.7 to 0.0 mm is formed in the contact hole 13. An alloy ball 22 made of 30% Mq-Affi of .8 um was inserted (
FIG. 2(a) diagram).

Next, the silicon substrate 11 was heat-treated at 510° C., which is slightly higher than the Mg-Aρ gold alloy melting point. At this time, the MQ-AQ alloy ball 22 is melted, and the contact hole 13 is filled with the MQ-A (1 alloy body 18) by subsequent cooling, as shown in FIG.

According to the second embodiment, unlike the first embodiment, MQA
The inside of the contact hole 13 can be filled with MO=AQ and the alloy body 18 without patterning ffilli and TiNIII.

Example 3 First, a silicon oxide film 12 with a thickness of about 1 μm is formed on a silicon substrate 11 on which a semiconductor element (not shown) is formed, and then a silicon oxide film 12 with an opening size of, for example, 1 μm×1 is formed in the oxide film 11112.
A contact hole 13 with a diameter of .mu.m was selectively formed using a photoetching technique.

Subsequently, after depositing a TiN film 14 as a barrier layer with a thickness of about 1000 on the silicon oxide film 12 including the contact hole 13, a TiN film 14 with a thickness of about 1000 is deposited on the entire surface by sputtering.
．． 5 μm 30% Mg-Aff alloy g! 15 was deposited (as shown in FIG. 3(a)). At this time, contact hole 13
While heating to 30% MQ- in the fvl-Aff
Pure AR was sputtered onto the i-alloy film 15 to a thickness of 0.5 μm.

At this time, the MO-Affi alloy film melts and the cavity 2
3 disappeared and the inside of the contact hole 13 was filled with the MQ-A2 alloy film. At the same time, pure Afill124 is deposited, and the molten M(MO in the ll-A2 alloy film diffuses into pure AR1I!24, resulting in MQ with an MQ content of 20%.
-AI2 alloy yield was 25 (as shown in Figure (b)). The melting point of this MO-A2 alloy 11!25 was 550°C.

Next, the pure A2 film 24 and the MQ film on the silicon oxide film 12 are
- The Affi alloy film 25 is etched back and removed, and the TiNIII4 on the silicon oxide l1112 is removed to form T + Nl114 only on the inner surface of the contact hole 13.
- remains in the same contact hole 13, and M
A tvl-Affi alloy body 26 with an O content of 20% was embedded (as shown in the same figure (C)).

Next, silicon oxide l containing the MCI-A2 alloy body 26! A 1 μm thick film is deposited on the MO-AR alloy body 26 by sputtering and patterned.
An A2 wiring 20 was formed to be directly connected to the A2 wiring 20 (as shown in FIG. 2(d)).

According to Example 3, MCJ-Aj2 alloy g1
When melting 15 and embedding it in the contact hole 13,
Since the pure A2 film 24 is deposited on the Mg-Aff alloy film 15, Mg in the I-AR alloy film is diffused into the pure A2 film 24, resulting in a low MO content (for example, MCI: 20%).
), that is, the Mg-AR alloy film 25 has a melting point higher than that at the time of initial deposition, and the contact hole 13 can be filled with the MO-Affi alloy body 26 having an Mg content of 20% by subsequent etchback. Therefore, since the MO-Affi alloy body 26 embedded in the contact hole 13 has a higher melting point than the Ma-A1 alloy body 18 of Example 1 described above, the heat treatment temperature after forming the wiring 20 was set as in Example 1. Can be made higher. Moreover, since the MQ content of the MO-A°C alloy body 26 can be reduced and the melting point can be increased, the MQ-Δλ
Even if the A2 wiring 20 is directly provided on the alloy body 26, the wiring 20
It is possible to suppress the diffusion of Mg into the A2 wiring 20 during the heat treatment after the formation of the TiN film 19 as in the first embodiment.

In addition, in the above-mentioned Example 2, MQ-A (
After inserting the alloy ball made of 1, the alloy ball was melted by heat treatment, but instead of the alloy ball, a lump alloy having another shape may be inserted into the contact hole.

In the above Example 3, in order to reduce the MO content in the MQ-AM alloy film, when sputtering pure AQM subsequent to the deposition of the Mq-An alloy film, the substrate temperature was kept at the same MQ.
Although a method of setting the temperature slightly higher than the melting point of the l;l-Aλ alloy film was adopted, the method is not limited thereto. For example, Mg
- After depositing a pure A2 film on the Affi alloy film, the substrate is taken out into the atmosphere and heat treated at a temperature slightly higher than the melting point of the Mg-An alloy film to melt the Mg-A42 alloy film and MQ in the alloy. may be diffused into the pure Aβ film, thereby reducing the Mg content.

In the above Example 3, a pure AQ film was deposited by sputtering on the M(J-Affi alloy film, but after the alloy film was patterned and left in the contact hole and its surroundings, a pure Aj2 film was deposited by sputtering. may be deposited.

In Example 3, the M9 content of the tvl-A2 alloy film under the pure AR film can be arbitrarily reduced by changing the temperature, film thickness, and time during sputtering of the pure AI2 film.

In each of the above embodiments, a silicon oxide film is used as the insulating film, but other insulating films such as a SiN film may also be used.

In each of the above embodiments, a case has been described in which contact is made with two wirings to a semiconductor element on a semiconductor substrate, but the same applies to a multilayer wiring structure such as connecting a first layer wiring and a second layer wiring. can.

(Effects of the Invention) As detailed above, according to the present invention, it is possible to provide a highly reliable and highly integrated semiconductor device from which highly reliable electrodes can be taken out even through minute contact holes.

[Brief explanation of drawings]

FIGS. 1(a) to (d) are cross-sectional views showing the manufacturing process of a semiconductor device in Example 1 of the present invention, and FIGS. 2(a) and (b)
FIG. 4 is a cross-sectional view showing the manufacturing process of a Mg semiconductor device in Example 2 of the present invention, and FIG. 4 is a cross-sectional view showing a conventional semiconductor device. 11... Silicon substrate, 12... Silicon oxide film,
13...Contact hole, 14...TiNII!
, 15.25...1vl-Affi alloy film, 18.2
6...MQ-A2 alloy body, 20...A2 wiring, 21
...WIl! i! , 22... alloy ball made of fvl-Affi, 24... pure A fil. Applicant's agent Patent attorney Takehiko Suzue (a) (b) (c) Figure 1 (a) (b) Figure 2 Figure 3 Figure 3 Figure 4

Claims (2)

[Claims] (1) An insulating film provided on a semiconductor substrate, a contact hole formed in this insulating film, a barrier layer provided at least at the bottom of this contact hole, and a layer embedded in the contact hole by melting. 1. A semiconductor device comprising: an aluminum alloy made of aluminum. (2) The semiconductor device according to claim 1, wherein the barrier layer is made of a film containing at least a nitride of a high-melting point metal, and the aluminum alloy contains magnesium.