JP2928409B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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 multilayer metal wiring.

[0002]

2. Description of the Related Art In recent years, in a semiconductor device, two or more layers of aluminum wiring have been frequently used in a semiconductor device due to a demand for miniaturization and high speed of the semiconductor device.

[0003] In a multilayer aluminum wiring, various flattening techniques are used so that a step in an upper aluminum wiring is not caused by a step in a lower aluminum wiring.

[0004] Among the flattening methods, the method shown in Fig. 1 is widely used for flattening using a coating film such as spin-on glass. However, in the above-described conventional method, water or SOG generated from spin-on-glass (hereinafter abbreviated as SOG) containing silanol as a main component during the process.
Due to the moisture adsorbed on the metal wiring layers, defects such as connection failure and disconnection are likely to occur in through holes connecting the respective metal wiring layers. Hereinafter, how a connection failure of a through-hole occurs in a conventional planarization technique will be described with reference to FIG.

[0005] Silicon substrate 1. After forming an element such as a transistor on the insulating film, 2. a first aluminum wiring having a thickness of 800 nm through 3. A first plasma oxide film is formed thereon at a deposition temperature of 390 ° C. using a known plasma CVD method. Is deposited to a thickness of 500 nm.

Next, a spin-on glass containing silanol as a main component. Is spin-coated on the flat portion to a thickness of 200 nm to fill the recesses and reduce the level difference.
Bake for 0 minutes. Water is generated by the dehydration condensation reaction of Si-OH in
5. To form a Si—O bond. However, the heat treatment at 450 ° C. does not complete the dehydration / condensation reaction, and Si—OH also exists in the film at the same time.

Most of the water generated in this baking step is released to the outside, but part of the first plasma oxide film 4.
And some of them are SOG5. It is taken in by itself and causes poor connection of through holes in a later process.
This stage is shown in FIG.

Next, at a deposition temperature of 390 ° C., a second plasma oxide film 6. Is deposited to a thickness of 500 nm, as shown in FIG. 5. Plasma oxide film Immediately before deposition, SOG5. 5. Water is generated again by the dehydration condensation reaction of Si-OH in the plasma oxide film immediately after. By deposition, S
Moisture is confined between the OG and the second plasma oxide film, and this moisture also causes poor connection of the through hole in a later step.

Next, in FIG. 1 (c), a through hole reaching the first aluminum wiring 7. And aluminum was deposited in a sputtering apparatus in FIG.
7. Second aluminum wiring by known photo-etching technology Is formed. In each of the aforementioned steps, S
OG5. Medium or plasma oxide film 4.6. The moisture taken in the second aluminum wiring 8. 6. Moisture blows out from the side wall of the through-hole due to a rise in temperature during vapor deposition of the through-hole. 6. Through holes due to the absence of aluminum on the side wall Cause poor connection. This example is shown in FIG.

In order to solve the above problem, a method has been proposed in which a part of the SOG is etched so that the SOG is not exposed on the side wall of the through hole. However, the number of steps is increased, and the SOG is etched. This method is not always effective because it has problems such as poor flatness.

[0011]

As described above, the conventional method for manufacturing a semiconductor device has a problem in that poor connection of through holes is likely to occur due to moisture caused by SOG.

An object of the present invention is to solve the above-mentioned problems and to provide a through-hole free from poor connection.

[0013]

According to the present invention, to solve the above-mentioned problems, a spin-on glass is applied to provide a through-hole free from poor connection, and then a dehydration-condensation reaction of Si-OH is caused at a high temperature to produce SOG. A step of baking and a step of removing water generated without causing a dehydration / condensation reaction of Si-OH at a subsequent low temperature. And a step of preliminarily heating up the deposition to deposit the insulating film in a short time.

[0014]

FIG. 3 shows a quadrupole analysis of the amount of water released when a sample obtained by applying SOG to a substrate to a thickness of 150 nm and then performing a heat treatment at 450 ° C. for 30 minutes in a nitrogen atmosphere is heated in vacuum. It was measured with a meter. The horizontal axis is temperature and the vertical axis is water release. The spectrum consists of two peaks, 25
Those having a peak at 0 ° C. are those from which moisture adsorbed on SOG has been desorbed, and those having a peak at 400 ° C. are Si-OH
Is the water generated by the dehydration condensation reaction of The peak at 250 ° C. disappears when the temperature is returned to room temperature once and the temperature is raised again, but those having a peak at 400 ° C. do not disappear.

In order to provide a through hole free from poor connection, it is necessary to thoroughly remove moisture remaining in the SOG or the insulating film in each heat treatment step. In the heat treatment applied to SOG, there are two types of temperature regions, namely, a temperature region in which moisture is generated by the dehydration condensation reaction of Si-OH and a temperature region in which only moisture taken in SOG is desorbed. By appropriately selecting the range, moisture remaining in the SOG or the insulating film can be minimized.

[0016]

1 shows a method of manufacturing a semiconductor device according to the present invention.
This will be described with reference to FIG.

Silicon substrate 1. After forming an element such as a transistor on the insulating film, 2. a first aluminum wiring having a thickness of 800 nm through 3. A first plasma oxide film is formed thereon at a deposition temperature of 390 ° C. using a known plasma CVD method. Is deposited to a thickness of 500 nm.

Next, spin-on-glass 5. 20 in flat area
Spin coating to a thickness of 0 nm to fill the recesses and reduce the level difference, then bake in a nitrogen atmosphere at 450 ° C. for 30 minutes. Water is generated by the dehydration condensation reaction of Si-OH in the SOG5. To form a Si—O bond. However, the heat treatment at 450 ° C. does not complete the dehydration / condensation reaction, and Si—OH also exists in the film at the same time. Most of the water generated in this baking step is released to the outside, but part of the first plasma oxide film 4. And some of them are SOG5. It has been captured by itself. Continue 0.6
Heat treatment is performed at 250 ° C. for 120 minutes while flowing nitrogen gas at 500 sccm under a reduced pressure of Torr. In this heat treatment, SOG5. Alternatively, most of the moisture remaining in the plasma oxide film is removed.

At 250 ° C., the dehydration condensation reaction of Si—OH hardly proceeds, so that water is newly generated, and SOG5.
3. Medium or plasma oxide film It is not taken in. This stage is shown in FIG.

Next, at a deposition temperature of 250 ° C., a second plasma oxide film 6. Is deposited to a thickness of 500 nm, as shown in FIG. 5. Plasma oxide film By setting the preheating up to the deposition to 30 seconds, SOG5. Water is not generated again by the dehydration-condensation reaction of the Si—OH therein.

Next, in FIG. 1 (c), a through hole reaching the first aluminum wiring7. And then nitrogen gas 500 scc under a reduced pressure of 0.6 Torr.
Heat treatment is performed at 250 ° C. for 120 minutes while flowing m. In this heat treatment, SOG5. Or, a plasma oxide film 4.6. Most of the water remaining in or adsorbed during the intermediate process is removed. Moreover, at 250 ° C., the dehydration condensation reaction of Si—OH hardly proceeds, so that water is newly generated, and SOG
5. Medium or plasma oxide film 4.6. It is not taken in.

After aluminum is deposited in a sputtering apparatus in FIG. 1D, a second aluminum wiring is formed by a known photo-etching technique. Is formed. In each of the above steps, SOG5. Medium or plasma oxide film 4.6. 7. Since the moisture taken in is sufficiently removed, the second aluminum wiring 6. Through-hole due to temperature rise during vapor deposition. 6. Water is blown out from the side wall, and the side wall of the through hole. 6. Through-holes such as aluminum not attached No connection failure is caused.

In the multilayer wiring structure thus obtained,
Even a fine through-hole having a diameter of about 1 μm is excellent in yield and reliability.

In the above embodiment, the case of SOG containing silanol as a main component has been described. However, it is needless to say that the present invention can be applied to SOG in which a part of silanol is substituted by a methyl group. In the above embodiment, a two-layer metal wiring is described, but the same effect can be obtained by applying the present invention to a multilayer wiring of three or more layers.

[0025]

According to the present invention, due to a rise in temperature during the deposition of the second aluminum wiring, moisture is blown out from the side wall of the through hole, which may cause poor connection of the through hole such that aluminum does not adhere to the side wall of the through hole. There is no. Further, in the multilayer wiring structure obtained in this way, even if the through-hole diameter is as small as about 1 μm, the yield can be improved.
It will be highly reliable.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a process sequence of one embodiment of the present invention and a process sequence of a conventional example.

FIG. 2 is a cross-sectional view illustrating a problem of a conventional example.

FIG. 3 is a diagram for explaining the amount of water release from SOG.

[Explanation of symbols]

 Reference Signs List 1 silicon substrate 2 insulating film 3 first aluminum wiring 4 first plasma oxide film 5 SOG 6 second plasma oxide film 7 through hole 8 second aluminum wiring

Claims (2)

(57) [Claims] A step of forming a first insulating film on a first metal wiring formed on a semiconductor substrate; a step of applying a spin-on-glass on the first insulating film; A first heat treatment step of baking at a temperature at which Si-OH therein causes a dehydration-condensation reaction, a second heat treatment step at a temperature lower than the baking temperature, which does not cause the dehydration-condensation reaction of Si-OH. Forming a second insulating film, forming a connection hole reaching the first metal wiring, continuously performing a third heat treatment in a temperature range that does not cause a dehydration-condensation reaction of Si—OH, and a second heat treatment step. A method for manufacturing a semiconductor device, comprising a step of depositing and patterning a metal wiring. 2. After baking the spin-on glass, the substrate is
A method for manufacturing a semiconductor device, comprising: depositing an insulating film in a temperature range in which a dehydration condensation reaction of i-OH does not occur and a preheating time.