JPH0243726A - Connection wiring formation - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] [Summary] The present invention relates to a method of forming a contact electrode in an element region typically formed on a silicon (Si) substrate, and aims to ensure the effectiveness of a barrier film. [Industrial Application Field] The present invention relates to the formation of interconnections, and in particular to the formation of interconnections for Si. Involved in barrier film formation for contact wiring.

In the past, AI was often used as a wiring material for semiconductor integrated circuits, but as integrated circuits become more dense and finer, alloys such as A7 or AI-3i, A7-3i-Cu are being used. ing.

This is Aj/S at a temperature of about 400℃ for pure AI wiring.
If interdiffusion of i occurs and the diffusion region is shallow, problems such as junction breakdown and short circuits will occur, so to prevent this, 1 to 2% Si is included in the AI wiring layer in advance. It is something.

As a result, the diffusion of Si into the AI was suppressed, but a new problem occurred: the growth of the Si layer. This is a phenomenon in which Si in the wiring layer grows crystals using the single crystal Si at the bottom of the contact hole as a nucleus, forming a new p-n junction and increasing contact resistance.

Therefore, in order to further deal with this problem, the barrier film is made of Si.
It was decided that it would be provided between the substrate and the A1 alloy wiring. As this barrier layer, compounds such as TiNTiC or T
i-W alloy is used. Since the specific resistance of these materials is on the order of tens of μΩ·cm, it is desirable to keep the thickness to the minimum required as a barrier in order to avoid high contact resistance.

Since TiN has poor adhesion with Si and high contact resistance with Si, in order to deal with this, a film of Ti or the like is further provided between the film and the Si substrate, so a barrier film is provided. The A1 alloy type connection wiring usually has a cross-sectional structure as schematically shown in FIG. Cough diagram 11
On the other hand, the TiN film has weak effectiveness as a barrier when a wiring alloy layer is deposited on the Si substrate after the TiN film is grown. Take it out and heat it at 450-600℃ in a N2 stream.
It is known that heat treatment is effective (for example, rwabuchi et al+ VLSI Sym
posium.

p. 55 (1986)). Similar treatment is Ti-W
It is also effective for membranes (e.g. V, Hoffman,
5solid State Technology, 8
Monthly issue, p58.1983. Japanese version).

It is not clear why this change in properties occurs due to treatment, but it is thought that oxygen enters the grain boundaries of TiN and suppresses the movement of Si and AI atoms ( (also called the stuff-fing effect).

[Prior Art and Problems to be Solved by the Invention] In order to obtain sufficient barrier properties of a film such as TiN, the sputtering process must be interrupted, the film must be taken out of the apparatus into the atmosphere, and heat treated. In order to perform deposition up to the wiring layer without taking the device out of the sputtering device, a heating device must be built into the sputtering device, but this heat treatment is performed at a high temperature of 450 to 600°C, and there is a device that can raise the temperature to this temperature. It is difficult to incorporate a heating device into a normal sputtering device.

In order to take out the material into the atmosphere during a vacuum processing process such as sputtering, it is not only necessary to simply break the vacuum, but also to prevent the adhesion of dust, which makes handling complicated and increases the number of steps. Become.

It is an object of the present invention to provide a new processing method that improves the properties of barrier films at lower temperatures, thereby making it possible to integrate a heating device within the sputtering equipment and simplifying continuous processing. It is an object of the present invention to provide a method for forming a connection wiring that is more stable and has a lower connection resistance in a process that is more stable and has a lower connection resistance.

[Failure to solve the problem]

In order to achieve the above object, the connection wiring forming method of the present invention includes forming an opening in an insulating layer covering a semiconductor substrate, depositing a film containing titanium as one of the main components, and then depositing the film containing titanium. The process includes a step of heat treatment in an atmosphere containing ozone.

The coating containing titanium is typically TiN, and TiC and Ti-W alloys are also subject to similar treatments.

Further, the processing temperature is about 300°C.

[For production]

As briefly mentioned above, the reason why the barrier properties are improved by heat-treating the barrier film in oxygen is that
Oxygen atoms enter the grain boundaries of the crystals that make up the TiN layer,
AI passing through grain boundaries by forming Ti oxides
This is thought to be due to the suppression of the spread of Regarding this point, in addition to the above-mentioned papers by Iwabuchi and Hoffman, W, 5inke et at App! , Phys.
, Lett, 47(5), p. 471 (1985).

In order for oxygen (0□) to be taken into the film from the atmosphere during heat treatment and for the oxidation of Ti to proceed, the temperature must be between 450 and 600°C.
It is necessary that On the other hand, ozone (03)
When heat treatment is performed in an atmosphere, since ozone is chemically more active than oxygen, oxidation of Ti at grain boundaries progresses even at temperatures of 300°C or lower, suppressing the diffusion of AI. It turns out.

〔Example〕

FIG. 1 is a schematic diagram showing the configuration of a processing device used for implementing the present invention. The general configuration of the device is a transfer chamber 2 provided in the center, and processing chambers 1a, 1bllc, and ld.
Si wafers, which are objects to be processed, are taken out one by one from a cassette loaded in the load lock 3, and are sequentially sent through the plurality of processing chambers. be processed. In one processing chamber, when one sheet is processed, the next sheet is processed. A gate valve is provided between each processing chamber and the transfer chamber.

Since the wafers loaded in bulk are processed one by one in this manner, this type of processing apparatus is called a single-wafer type.

The treatments in each of the above processing chambers include sputtering of a Ti film in 1a, sputtering of TiN in 2b, heat treatment in an ozone atmosphere in lc, and sputtering of an A1 alloy in 1d. Details of each treatment will be made clear during the description of the example steps later.

FIG. 2 is a schematic cross-sectional view showing the process of an embodiment in which the present invention is applied to S/D fil area contact wiring of a MOS transistor. Reference is made to FIG. 1 for the relevant parts.

FIG. 2 (al is a Si substrate 11 with a selective oxide film 12 for element isolation, S/D regions 13 and 14, a gate insulating film 15, a poly-Si gate electrode 16, and an SiO□ layer 17 which is an interlayer insulating film)
It shows a state in which layer type 7 is formed and S/D contact holes are opened. Up to this point, the processing is proceeded by a known method.

Ten feet of Si wafers in this state are loaded into the load lock 3 shown in FIG. 1, and one of the wafers is sent to the spuck processing chamber 1a via the transfer chamber 2 by a transfer device (not shown).

In the processing chamber, a Ti film 1 is formed using pure argon as a sputtering gas.
8 is formed to a thickness of 500 people.

Next, the wafer is sent to the sputtering chamber 1b by the above-mentioned transport device, where it is filled with argon and nitrogen (mixing ratio: l:
1) as a sputtering gas, 1000 to 2000 TiN1 at a pressure of 1 to 10 mTorr and a sputtering power of up to 5 KW.
9 is deposited and formed.

The subsequent treatment performed in the treatment chamber 1c is ozone oxidation treatment, which is the main requirement of the present invention. Ozone is generated by an ozonizer 4 using oxygen as a raw material, and the ozone pressure in the processing chamber is maintained at 1 to 10 Torr. The Si wafer is heated to 300° C. by the heat stage 6, and oxidized with ozone. The processing time is ~3 minutes including the time required to raise the temperature of the wafer.

A temperature of about 300° C. is a temperature that is used as a substrate temperature even in ordinary sputtering, and can be easily achieved even in a sputter processing chamber by a commonly used heating means. In addition, 5a.

5b and 5d are targets for each sputtering described above.

The oxidized wafer is transferred to a processing chamber 1d, and an Al-3 layer alloy 20, which is a wiring layer, is deposited by sputtering to a thickness of 1 μm. This processing condition may be the same as usual.

Through the above processing, as shown in Figure 2 ('b),
Three layers of Al-5i/TiN/Ti are deposited and patterned to complete a MOS transistor with contact wiring as shown in FIG. 2(C).

The contact resistance between the S/D region of the MOS transistor thus obtained and the AI wiring is 1×10Ω・
It showed a value of about Cl1l-2, and no increase in resistance value was observed even after heat treatment at 550°C. Incidentally, when the TiN film is not subjected to oxidation treatment, the characteristics of the transistor begin to deteriorate even after heat treatment at 500°C.

Although the above embodiment was applied to TiN, the same effect can be obtained by applying similar processing to TiC. In that case, the TiC film can be formed by reactive sputtering using a mixed atmosphere of argon and methane as the processing gas in the processing chamber 1a of the above embodiment.

〔Effect of the invention〕

As explained above, according to the present invention, Ti such as TiN
It is possible to improve the properties of a barrier film whose main component is heat treatment at a relatively low temperature, and by incorporating a heating device into a single-wafer sputtering system, the number of processing steps can be increased and the process complicated. Therefore, it is possible to form contact wiring with excellent characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram showing the configuration of an apparatus for carrying out the present invention, FIG. 2 is a cross-sectional diagram showing the steps of an example, and FIG. 3 is a cross-sectional diagram showing the structure of A1 alloy wiring. 18 to 1d are sputtering chambers, 2 is a transfer chamber, 3 is a load lock, 4 is an ozonizer, 5a, 5b, and 5d are targets, 6 is a heat damage, 11 is a silicon oxide film, 12 is a selective oxide film, 13.14 is the S/D region, 15 is the gate insulating film, 16 is the gate electrode, 17 is SiOz, 18 is Ti3. 2Etsu 1st [21 亥)Color ◇1) /l L Simple surface owl 2nd without showing the degree
2 Figure

Claims (1)

[Claims] After forming an opening in an insulating layer covering a semiconductor substrate and depositing a film containing titanium as one of its main components, the film containing titanium as one of its main components is exposed to at least ozone. 1. A method for forming a connection wiring, the method comprising the step of heat treatment in an atmosphere containing: