JPH0465823A - Method and device for manufacturing semiconductor element - Google Patents

Abstract

PURPOSE:To prevent a target from being contaminated and improve the throughput and the step coverage at a level difference of a high aspect ratio by using a mixed gas of helium and nitrogen as the sputtering gas to be used at the time of forming a TiN film and introducing O2 gas into the device used for the sputtering immediately after the TiN film is formed while the interval between the target and a wafer is expanded to twice or thrice of a mean free stroke. CONSTITUTION:Process devices 12-15 used at each process in the course of manufacturing semiconductor elements are collectively provided in one chamber 10 in which the devices 12-15 are blocked from the outside air and their degrees of vacuum can be controlled collectively. A processing chamber 14 is constituted to such a differential exhausting structure that the degree of vacuum can be controlled independently from other processing chambers 12, 13, and 15 and O2 gas can be introduced into the chamber 14. At the time of forming a TiN film, the film is formed by a reactive sputtering method using a mixed gas composed mainly of helium mixed with N2 gas and the gas atmosphere is immediately switched to an O2 gas atmosphere without exposing the substrate to the outside air immediately after the TiN film is formed. At the of performing the sputtering of Ti, TiN, and Al, in addition, the interval between a wafer and target is set to the twice or thrice of a mean free stroke calculated from an equation 5.8X10<-3>/sputtering pressure = lambda.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method of manufacturing electrode wiring in a semiconductor element and a manufacturing apparatus involved in the manufacturing.

(Prior Art) A method for manufacturing electrode wiring in a semiconductor device is shown in FIG. 2 as a cross-sectional view of the main parts.

First, as shown in FIG. Using the sputtering equipment shown in the figure, titanium (Ti) 4 was deposited to a thickness of approximately 500 mm by reactive sputtering to obtain ohmic properties, and then titanium nitride (TiN) was deposited as a diffusion barrier for aluminum 1 (AI) 6 for wiring. 5 was also deposited to a thickness of about 1,500 layers using the reactive sputtering method. Subsequently, this substrate (wafer) is first taken out of the sputtering apparatus, and the TiN film 5 is made to absorb oxygen gas.

Since a TiN film sputtered without applying a substrate bias is a porous film with columnar crystals, it is known that it absorbs oxygen gas when left in the atmosphere.

As a result, heat resistance improves (this is called the oxygen stack method).

Next, as shown in the figure (b), the wafer thus formed is again loaded into the sputtering apparatus to form an AI film 6 to a thickness of 1 μm. After that, photolithography, etching technology (RI
The A16, TiN5, and Ti films 4 are formed into a wiring pattern using method E).

The conditions for forming the Ti film 4 and the TiN film 5 by sputtering are as follows: For Ti, the DC power is 2 kW, the sputtering atmosphere is Ar, the pressure is 7 mTorr, and the temperature is 50 mTorr without heating the substrate.
After that, using the same Ti target, the power was 1.8 kW, and the sputtering atmosphere was made into a mixed gas of Ar and N2. The N2 gas partial pressure is 30% of the total pressure (7 mTorr x 0.
3 = 2.1 mTorr), then put Ar gas and
The TiN film was heated to 15 mTorr without heating the substrate.
Deposit 00 people. It has been confirmed by Auger spectroscopy that a stoichiometric TiN film is formed when the N2 gas partial pressure is 25% or more of the total pressure.

Furthermore, the distance between the Ti target 32 and the wafer 31 in the sputtering device (Fig. 3) is usually set to 5 to 10 cm, and the mean free path (λ) when the Ar gas pressure cuff is mTorr is λ = 5. .8X I O-”/P41
Since cmP is sputtering pressure, L>5.

Note that the description of the conventional sputtering apparatus shown in FIG. 3 is a schematic diagram of a very general apparatus, so detailed explanation will be omitted. In short, it is an apparatus that deposits a necessary material on the wafer 31 by so-called sputtering, which is installed at a certain distance from the target 32 of the material to be sputtered on the wafer 31 and applies a voltage to discharge the material.

(Problem to be solved by the invention) However, the above method has the following problems.

(1) When forming a TiN film by reactive sputtering, N2 gas, which is lighter than Ar gas, tends to adhere to the target, so neutral N2 molecules and N2 ions collide with the Ti target, causing the target surface to become nitrogen-rich. Ohmic properties cannot be achieved because the contaminated Ti film is deposited as it is. Therefore, it is necessary to clean the contaminated Ti target by empty deposition.

(2) As mentioned above, since the TiN film just after being formed has poor heat resistance, it must be exposed to the atmosphere and stacked with oxygen before depositing the AI film, resulting in a decrease in throughput.

(3) In a normal sputtering device, the distance between the target and the sea urchin is more than five times the mean free path, so the metal particles collide with each other multiple times. Therefore, there is almost no vertical incidence on the wafer, resulting in so-called oblique sputtering, so that the step coverage in a contact hole having a high aspect ratio may be extremely reduced due to the self-shadowing effect.

(Means for Solving the Problems) The present invention solves the above-mentioned problems, namely (1) target contamination, (
2) Continuous sputtering of Ti, TiN%AI film is not possible, (3)
In order to solve the problem of poor step coverage of contact holes, the following method and apparatus are provided. That is, (1) using a mixed gas of He (helium), N, (nitrogen) as a sputtering gas when forming the TiN film; (2) introducing 02 gas into the sputtering apparatus immediately after forming the TiN film; The present invention provides a manufacturing method including (3) and increasing the distance between the target and the wafer by two to three times the mean free path (λ), and also provides a manufacturing apparatus therefor.

(Function) Since the present invention employs the above-described manufacturing method and manufacturing apparatus, N2 gas and Ti, which are heavier than He, tend to not adhere to the target and reach only the substrate during TiN film formation, thereby preventing contamination of the target. can do.

In addition, since the TiN film is exposed to a vacuum 02 gas atmosphere and stacked with oxygen, the throughput is improved.

Furthermore, since the distance between the target and the wafer is shortened, the vertical incidence component of metal particles on the wafer increases, improving step coverage at high aspect ratio steps.

(Example) FIG. 1 shows a conceptual diagram of a manufacturing apparatus for implementing the present invention. The cross-sectional view of the manufacturing process of the semiconductor element itself is similar to the cross-sectional view of FIG. 2, so that figure will not be particularly described.
The manufacturing process will be explained with reference to FIG. 2, focusing on the manufacturing apparatus of this embodiment shown in FIG. The manufacturing apparatus of this embodiment shown in FIG. 1 is a conceptual diagram thereof, and is one of the so-called multi-chamber systems that have appeared in recent years. That is, various process equipment (third
(similar to the one shown in the figure) are installed in a single vacuum device (chamber) that is isolated from the outside air and whose degree of vacuum can be controlled collectively.

In this embodiment, as shown in the figure, one chamber 10 is provided with a load rotor chamber 11 for loading and unloading wafers, and various process chambers 12 to 15 to be described later.

As for the evacuation system, the entire chamber 10 is roughly evacuated by a rotary pump 17 and main evacuated by a cryopump 18, but the load-lock chamber 11 and the process chamber 14 are separated from each other as described below. That is, the load lock chamber 11 is configured to be evacuated only by the rotary pump 17, and the process chamber 14 as a deposition chamber is evacuated by the turbo pump 19 and the rotary pump 20.
The structure is configured to perform differential pumping. In other words, it is a system that is separate from the other process chambers 12, 13, and 15, and has a mechanism in which the degree of vacuum can be controlled independently.

As shown in the figure, the gas system is equipped with N2 in the load lock chamber 11.
gas 25, Ar gas 26 in the process chamber 12 as a cleaning chamber, N2 gas 25, Ar gas 26, and H in the process chamber 13 as another deposition chamber.
A mechanism is used to introduce e gas 27 and Ar gas 26 into the process chamber 15, which serves as another deposition chamber.

02 gas 2 is placed in the process chamber 14 which is differentially pumped.
3 and Ar gas 26 can be introduced while being controlled independently from other chambers by a baratron sensor 21 which is a pressure sensor and a baratron controller 22 which controls the baratron sensor 21.

Although the introduction of each gas into the process chambers 12, 13, and 15 is not shown, it goes without saying that the gas pressure is controlled by a baratron controller.

In addition, although this is also not shown, the distance between the target and the wafer in each process chamber, that is, the distance L shown in FIG. The mechanism is such that it can be adjusted to 2 to 3 times the confession distance, that is, 2 to 3 cm.

(L=(2-3)Xλ) This is a mechanism that simply shortens the distance and can be easily adjusted.

The process of manufacturing the electrode wiring section in this example using the apparatus described above will be described below.

First, the wafer shown in FIG.
1 and then process chamber 1 as a cleaning chamber.
Move to 2. Therefore, after the base pressure is evacuated to below 1X10-'Torr (by rotary pump 17 and cryopump 18), Ar gas 26 is introduced, and degassing processing is performed by baking.

Next, it is transferred to the process chamber 13 where deposition is performed,
Titanium 4 was deposited to a thickness of 500 mm by applying DC 2 kW to the titanium target at an Ar pressure of 5 mTorr. Next, once the temperature was reduced to below lXl0-'Torr by evacuation, N2
Gas 25 is introduced and the pressure is 2.1 mTo, which is 30% of the total pressure.
After adjusting to rr, He gas 27 was introduced and the temperature was 7 mT.
Control to o r r. And 1 on TL.
Apply 8kw of power and self-bias 10 to the substrate.
A TiN film 5 is deposited to a thickness of 1500 mm by reactive sputtering while applying 0 V.

Thereafter, the sputtering discharge is stopped, the He and N2 gases are cut off, and the wafer is evacuated and at the same time the wafer is transferred to the process chamber 14 where the next deposition will be performed. Therefore, 02 gas 23 was introduced, and 30
This is maintained for a second to occlude 02 into the TiN film 5.

Next, the wafer that has been processed up to the above is transferred to a process chamber (deposition chamber) 15 maintained at a temperature of 150°C,
Al film 6 is sputtered with AI tutter to a thickness of 1.0 μm.
deposit

Finally, it is transferred to the load lock chamber 11, cooled, and then taken out from the chamber 10 through the N2 gas vent (25).

In the subsequent steps, a wiring pattern is formed in the same manner as in the conventional method.

Although not specifically described, such multi-chambers are generally isolated from the outside air, and the transfer of wafers within them is automatically controlled without human intervention.

(Effects of the Invention) As explained above, according to the present invention, there are the following effects.

(1) Since a He-based mixed gas of He and N2 was used to form the TiN film, N2 gas, which is heavier than He, and Ti
tends to reach only the substrate without adhering to the target. That is, the target is not contaminated. Furthermore, applying a substrate bias also works more effectively to prevent N2 contamination on the target.

(2) After the TiN film is deposited, the vacuum state is not stopped and the film is exposed to the 02 gas atmosphere to stack oxygen, which improves the throughput compared to once exposing it to the atmosphere.

(3) Since the distance between the target and the wafer is shortened, there are many vertically incident components of metal particles to the wafer, and step coverage at high aspect ratio steps is improved.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an apparatus according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of an electrode wiring process, and FIG. 3 is a diagram showing a conventional sputtering apparatus. １・・・・・・・・・Substrate, ２・・・・・・・・・
Insulating film, 3...Contact hole, 4...
・・・・・・Ti, 5・・・・・・・・・Ti
N. 6・・・・・・-・A1. 10・・・・・・・・・
Chamber, 111...Loadlock chamber,
12.13.14.15... Process room,
23...02 gas, 25-...-...
N2 gas, 26...-Ar gas, 27...
...He gas, 31...Wafer,
32...Target. Figure 2: Process cross-sectional diagram of electrode arrangement*

Claims (2)

[Claims] (1) When forming electrode wiring using Ti, TiN, and Al films in semiconductor devices, (a) When forming a TiN film, He-based He
(b) Immediately after forming the TiN film, the gas atmosphere is changed to O_2 gas without exposing the substrate to the atmosphere; (c) Ti , when sputtering TiN, Al, the distance between the wafer and the target is set to 2 to 3 times the mean free path calculated by 5.8 x 10^-^3/sputtering pressure = λ. A method for manufacturing a semiconductor device. (2) As a multi-chamber system that has multiple process chambers for semiconductor device manufacturing and is completely isolated from the outside air, (a) Ar, N_2, He,
It is possible to introduce gases, mix them, and control the pressure of the mixed gas; (b) It has a differential exhaust system that can control the high gas pressure, which is different from the gas pressure of the entire multi-chamber, independently from other process chambers. (c) The multi-chamber as a whole has at least two or more types of sputtering targets.