JPH03120357A - Thin film forming device - Google Patents

Abstract

PURPOSE:To inhibit the generation of foreign matter and to form a barrier layer having high reliability by providing an exhaustible preliminary chamber on the adjacent first and second reaction chambers and moving a substrate to both directions. CONSTITUTION:Silicon wafers 12 are carried from a first load locking chamber 1 and thin films such as Ti are formed in the first reaction chamber 6. Thin films such as TiNx are formed in the second reaction chamber 16. Silicon wafers 24 with barrier layers formed thereon are taken out from a second load locking chamber 19. Then the other silicon wafers are introduced from the second load locking chamber 19 and the silicon wafers are moved to the direction reverse to the above-mentioned process and the barrier layers are formed thereon. Thereby a target in the same reaction chamber is utilized and only gaseous pure Ar is introduced and Ti sputtering is performed. TiN sputtering can be performed by mixing gaseous N2. Nitride formed on the surface of the target at the time of TiN sputtering is flown at the time of Ti sputtering by alternately performing the stage. The surface of the target can be always cleaned.

Description

[Detailed description of the invention] [Industrial Application Field J The present invention relates to a metal thin film forming apparatus.

In particular, the present invention relates to an apparatus suitable for forming barrier layers used in semiconductor integrated circuits.

[Conventional Technique #] 31st NR is a diagram showing a schematic configuration of a conventional multi-chamber one-type sputtering apparatus. This device consists of a load lock chamber (25), a first reaction chamber (6), and a second reaction chamber (
16) and an unload lock chamber (27). In this case, the process proceeds from the right side to the left side in the figure. Although the transport mechanism between the vacuum chambers is not shown, for example, an arm-type transport means is used.

A cassette holder (2) is installed inside the load lock chamber (25), and an exhaust pipe (13a) is connected to the bottom of the chamber so that the interior of the chamber is exhausted from this part.

The load lock chamber (25) K is the first square cassette (4).
) through the loading port (26), and the silicon wafers (12) stored in this first wafer cassette (4),
The mechanism is such that the feeder is delivered to the first reaction chamber (6). This is K
Therefore, processing can be performed without exposing the first reaction chamber (6) to the atmosphere.

Inside the first reaction chamber (6), an aperture (7) is placed at the top and an anode (8) is placed at the bottom, facing each other and spaced apart from each other by a predetermined distance. Yin i (F is the target (9) and the target support stand that supports it (
1O). The target (9) is a raw material for a metal thin film to be formed on the silicon wafer (12), and titanium (T1) is used here. Yang FM
(8) has a structure in which a silicon urchin (12), which is a substrate to be processed, is placed and fixed on a substrate holder (11). Cathode (7) and positive! (8) are each connected to a power source (not shown), and a predetermined voltage is applied between these two electrodes. An exhaust pipe (13b) is connected to the bottom of the first y-th reception chamber (6). In addition, since an inert gas, such as argon (hereinafter abbreviated as Ar) gas necessary to cause sputtering on the upper part, is supplied to the internal IF of the first reaction chamber (6), the vacuum pulp (14
) is installed. The first gate pulp (15) is provided between the load lock chamber (25) and the first reaction chamber (6).
) is normally closed and the load-lock chamber (
25) and the first reaction chamber (6).
2) It is opened when handing over.

In the first reaction chamber (6), in this case, silicon cueva (1
2) Form a titanium thin film on top.

The second reaction chamber (16) has the same basic configuration as the first reaction chamber (6). However, the following points differ from the first reaction chamber (6). That is, in the upper part of the second reaction chamber (16), necessary for causing reactive sputtering,
The vacuum pulp (1
7) is installed. As a result, the second reaction chamber (16)
In this case, a titanium nitride thin film is formed.

A cassette holder is installed inside the unload lock chamber (27), and an exhaust pipe (13d) is connected to the bottom. The unload lock chamber (27) is a second reaction chamber (
16) after completing the film formation without exposing it to the atmosphere.
The wafer (24) is carried out of the Nuvatuta apparatus through the carry-out port (28). The second cassette case (22) installed in the cassette holder (2) K accommodates the silicon wafer (24) on which film formation has been completed.

According to this apparatus, a titanium thin film is formed in the first reaction chamber (6), and a titanium nitride thin film is formed in the VKK second reaction chamber (16).

Next, an example of forming a semiconductor device using this apparatus will be described. FIG. 4 is a sectional view of the main parts of the semiconductor device.

In this case, the barrier layer (27) is, for example, a wiring layer (27) made of aluminum and silicon in a semiconductor device.
This is formed to prevent alloy spikes from forming from 301 to the underlying substrate (32).

Here, a method for forming the above-mentioned main parts will be explained.

First, an interlayer insulating film (31) is formed on a substrate (32), and a contact hole (33) is formed therein. A barrier layer (27) is formed on the surface of this contact hole (33).
is formed.

Next, the process for forming this barrier layer (27) will be explained in detail. Silicon wafer (12
) into the load lock chamber (2).
5) and lock the inside of the load lock chamber (25) to 10″TOπ.
Exhaust to a certain extent. This causes the first gate pulp (1
Even if 5) is opened, the atmosphere is not allowed to flow into the first reaction chamber (6), making it possible to form a highly reliable thin film. First reaction chamber (6)
was pre-evacuated and heated in an Ar gas atmosphere for 10" to 1
The pressure is adjusted to about 0-" Torr. After the load lock chamber (25) is evacuated, the silicon wafer (12) is carried into the first reaction chamber (6).
In an r gas atmosphere, a voltage of K (7) and (8) is applied to perform sputtering. In the first reaction chamber (6), a titanium (hereinafter abbreviated as T1) thin film (28) is formed with a thickness of 100λ. This T1 thin film (28) is made of silicon (1
2) This is to improve the film adhesion of

In the first reaction chamber (6), T1 is placed on the silicon wafer (12).
After forming the thin film (28) to a predetermined thickness, the silicon wafer (23) on which the T1 thin film (28) has been formed is transferred to the second reaction chamber (16). The second reaction chamber (16) has a K, 10-2 to 10''TorrOA similar to the first reaction chamber (6).
It's a nice atmosphere. However, silicon wafer (23)
After bringing in and closing the second gate pulp (18),
Open the vacuum pulp (17) and supply N2 gas to the 2nd y reaction chamber (1).
6) Introduce K.

At this time, while keeping the degree of vacuum constant, the second gas is introduced at a volume ratio of about 10 to 50% of the M gas.

This N2 gas becomes a reactive gas component when performing reactive sputtering, and causes a chemical reaction with T1 to form titanium nitride (hereinafter referred to as TiN).

In this state, a voltage is applied to the electrodes (7) and (8) to perform reactive sputtering to form a thin film of about L000^ on the Crycon wafer (23). Here, the formed thin film contains T1 as well as TiN, so Ti
Nx, T29). After film formation, vacuum pulp (17
) is closed, and the inside of the second reaction chamber (16) is again made into an Ar gas atmosphere. This is to prevent N2 gas from flowing into the first reaction chamber (6) when the second gate pulp (18) is opened and closed. Silicon wafers (2
4) is transferred to the unload lock room (26) and
It is housed in a Kueha case (22). The unload lock chamber (26) is evacuated to about 10-6 Torr after the second case (22) is installed therein in advance to prevent atmospheric air from flowing into the second reaction chamber (16). After storing the silicon cube (24) after film formation in the second wafer case (22), it is placed in the third gate bulk (20).
), the unload lock chamber (27) is returned to atmospheric pressure, and the deposited silicon wafer (24) is transferred to the unloading port (28).
The above is the method for forming the barrier layer (27) using the multi-chamber sputtering apparatus t-m. By this processing method, the remaining unprocessed silicon wafers (12) are sequentially processed.

Here, the film forming machine WK in reactive sputtering will be explained. FIGS. 5 to 7 are diagrams schematically showing a film forming mechanism of reactive sputtering. First, after evacuating the reaction chamber to about 10" Torr or less, Ar gas is introduced and the reaction chamber is adjusted to about 10-3 Torr (1N). In this state, when a predetermined voltage is applied between the electrodes (force, (8)) , Ar, and N2 are ionized and a plasma (34) is generated (Fig. 5).At this time, Ar+ (argon ions) are accelerated toward the cathode by electric attraction, and the cathode, in this case,
Collision with target (9).

However, since K Ar+ returns to Ar just before the collision, it does not react with the target material, T1 in this case.

The impact of the collision at this time causes the T1 atoms (35) to be blown away from the surface of the target (9). (Figure 6).

Among these ejected T1 atoms (35), near the anode, in this case the silicon wafer (23), nitride ions (N-),
! : K36), or by collisional reaction with C2, Ti
N and adheres to the silicon wafer (23) (7th
Figure) 5 This process is repeated to form a T18x thin film (29) on the silicon wafer (23). However, some of the T1 atoms (35) that have jumped out from the surface of the target (9) do not cause a chemical reaction in the vicinity of the Crycon wafer (23), and some T1 atoms (37) directly adhere to the Crycon wafer (23). Therefore, #III to be formed also includes T1, and here, TiNx and four films are shown. In this way, the barrier layer (27) is placed on the substrate (32).
) is formed, patterning is performed using a photo-ring fibrillation technique to form a barrier layer (27) in a predetermined pattern. After this, this patterned barrier layer (
27), and are patterned to form a predetermined distribution Am (30).

(Problem to be solved by the invention J) The conventional sputtering apparatus is configured as described above, and when forming the barrier layer (27) with this multi-chamber type sputtering apparatus, the reaction is always carried out in the second reaction chamber (16). However, when sputtering is performed, the result is K.
If reactive sputtering is continued, after the cumulative number of processed wafers reaches a certain number Ks, the number of foreign substances adhering to the Cricon wafer (23) increases rapidly. FIG. 8 shows the situation at this time, with the horizontal axis representing the cumulative number of processed sheets and the vertical axis representing the number of foreign objects. In this example, the number of foreign particles suddenly increases after the cumulative number of processed sheets is around 50.

This phenomenon occurs as follows. Second reaction chamber (16
), KN2 gas is introduced every time the film is formed. However,
Since T1, which is the material of the target (9), is a highly reactive metal, a chemical reaction occurs on the surface of the target (9) to form TiN. In addition, as mentioned in the conventional technology, in % reactive sputtering, the cricon wafer (23)
A T1 layer is formed near the surface and adheres to the surface of the cricon wafer (23), but a similar phenomenon occurs, albeit in a small amount, on the surface of the target (9). These reactions are
The 62 partial pressure in the second reaction chamber (16) is 10-2~10=T
Since the amount of oxidation is low (orr), it does not occur in large quantities in a relatively short period of time. However, as the cumulative number of sheets processed by reactive sputtering increases and the target (9) is exposed to N2 gas for a long time, the surface of the target (9) gradually becomes Ti.
The N compound comes to cover a wide area. Therefore, T1 and Ti
The mixture with N adheres and the target is sputtered, resulting in the adhesion of TiH foreign matter formed on the target (9) surface onto the silicon wafer (23) surface.

Processing under such a phenomenon causes a deterioration in the quality of the TiNx ill film, and there is a problem in that the reliability of the formed semiconductor device is likely to be impaired.

The present invention has been made to solve the above-mentioned problems, and when forming a barrier layer using a multi-chamber method, it suppresses the generation of foreign matter during reactive sputtering and makes it possible to form a high-quality TiNx thin film. It is an object of the present invention to provide a thin film forming method and a thin film forming apparatus used therein in which high reliability can be achieved.

[Means for solving the problem] A thin film forming apparatus according to the present invention has a parallel plate IE pole,
A first reaction chamber into which gas to generate plasma and nitrogen gas contributing to a film formation reaction to be formed on a substrate to be processed can be introduced, and a second reaction chamber are arranged adjacent to each other. A pre-wiring chamber is provided in each of the first reaction chamber and the second reaction chamber, which can be evacuated and where the substrate is carried in and out, and the substrate is transferred from one pre-chamber to the other. It can be transferred to the preliminary chamber in both directions, and film formation is performed by transferring from one direction or the opposite direction.

[Operation] In the present invention, using targets in the same reaction chamber, Ti sputtering can be performed by flowing only pure Ar gas, and TiN sputtering can be performed by mixing N2 gas. By performing this process alternately, nitrides formed on the target surface during TiN bubbling are removed during T17 bubbling, and the target surface can always be kept clean. This makes it possible to form a barrier layer with high reliability.

〔Example" Hereinafter, embodiments of the present invention will be described with reference to the drawings.

Note that the description of parts that overlap with the description of the conventional technology will be omitted as appropriate.

FIG. 1 is a diagram showing a schematic configuration of a multi-chamber type sputtering apparatus according to the present invention.

The configuration of this device differs from the conventional multi-chamber type in the following points. First, a vacuum valve (17) is installed to introduce KN2 gas into the upper part of the first reaction chamber (6).
The first reaction chamber (6) and the second reaction chamber (16) have the same structure. In addition, the part corresponding to the unload lock chamber (27) of the conventional technology was replaced with the 20th lock chamber (19).
) Each load-lock chamber in this device has the functions of a conventional load-lock chamber (25) and an unload-lock chamber (27). Although not shown, for example, an arm system or a belt system is used as the transport means, and silicon wafers (
12) to have a transport function that allows transport in both directions.

It is. Therefore, with the above configuration, the silicon wafer (12) can be processed from the right side in the figure to the left side, or from the left side to the right side in the figure.

Next, the process of forming a barrier layer (27) on a silicon wafer (12) when forming, for example, the structure shown in FIG. 4 will be described. First, the silicon wafer (
12) is carried in from the 10th dock chamber (1), a TiNX thin film is formed in the first reaction chamber (6) to a thickness of about 100x, and then a TiNX thin film is formed in the second reaction chamber (16). 1, 0
It is formed to a film thickness of about 00x, and the 20th drop chamber (19
) The silicon wafer (24) on which the barrier layer (27) has been formed is taken out from Ic. The above processing is similar to the conventional technology. For example, the silicon wafer (12)
Continue until 25 sheets are processed. As described above, herein, the case where processing is performed from the right side to the left side in the figure is referred to as a right turn process.

Next, a silicon wafer (12) to be deposited, which is different from the one described above, is put into the 20th draw chamber (19), and this time it is carried out in the opposite direction to the above process, that is, from the left side to the right side in the figure.
A silicon wafer (12) is transported and a barrier layer (27) is formed. This is referred to herein as the left-turn process in contrast to the above. Barrier layer for left turn process (
27) is formed using K as follows.

First, the second wafer cassette (22) containing the silicon wafer (12) on which a film is to be formed is placed in the 20th draw chamber (19).
) Insert K, 10-' inside the 20th drawer chamber (19)
Evacuate to a vacuum pressure of about vrorr. As a result, even if the third gate valve (20) is opened, the second reaction chamber (1
6) It is possible to form a highly reliable thin film without allowing air to flow into the film. The second reaction chamber (16) is evacuated in advance,
The vacuum pressure is adjusted to about 10-2 to 10-'' Torr in a red gas atmosphere.
9) After the inside of the silicon wafer (1) has been sufficiently exhausted,
2) is carried into the second reaction chamber (16). At this time, the vacuum valve (17) is kept closed and no N2 gas is introduced.

From this K, the electrode (7) is placed in the above Ar gas atmosphere.

(8) Apply K voltage and perform sputtering to form a TiN film (30) in the second reaction chamber (16). The thickness of the T1 thin film (30) at this time is approximately 1001 mm as in the case of film formation by the light turn process. In the second reaction chamber (16), a T1 thin film (3
0) to a predetermined thickness, the silicon wafer (23) is transferred to the first reaction chamber (6). First reaction chamber (6)
Similarly to the second reaction chamber (16), 10" to 10'To
This is done in an Ar gas atmosphere with a vacuum pressure of about rr. Here, the structure is such that N2 gas can be introduced by opening the vacuum pulp (17) in the first reaction chamber (6). That is, a silicon wafer (23) with a T1 thin film (30) is carried in, and a second gate valve (18
), the vacuum pulp (17) is opened and N2 gas is introduced into the first reaction chamber (6)K. At this time, while keeping the degree of vacuum constant, N2 gas was added at a volume ratio of 1 to Ar gas.
0 to 50%, voltage is applied to the electrodes (7) and (8), and reactive sputtering is performed. The reaction mechanism in this first reaction chamber (6) is similar to the reaction mechanism in the second reaction chamber (16) in the light turn process.
The film thickness of the TiNx N film (31) at this time also depends on the film formation time of the silicon wafer (23) by the light turn process.
The film is formed to have a thickness of about Kx, oooX. After film formation, the vacuum pulp (17) is closed and the first reaction chamber (16
) to create an Ar gas atmosphere. This is to prevent the 82 gas from flowing into the second reaction chamber (16) when the gate valve (1B>) of @2 is opened and closed. The wafer is carried out to the 10th storage chamber (1) and stored in the first wafer cage (4).The 10th storage chamber (1) is heated to a temperature of about 10' Torr after the first wafer cage 7 (4) is installed in advance. The first reaction chamber (16) is evacuated to a vacuum pressure of
4) in the first wafer case (4), the first gate valve (15) is closed, and the 10th wafer chamber (25) is closed.
) was returned to atmospheric pressure, and the silicon wafer (24) on which the film was formed
Open the carry-in/out entrance (5) and carry it out of the equipment. The above is the barrier layer (27) forming step in the left turn process.

Similar to the phytoturn process, this process is continued until, for example, 25 sheets are processed.

After finishing the left turn process, the silicon cueva (xz) tl should be processed again by the phytoturn process.
tlJrflllxfru. Thereafter, a left turn process and a right turn process are performed alternately.

By alternately performing the right turn process 5 and the left turn process as described above, the first reaction chamber (6)
and the second reaction chamber (16), T1 sputtering and TiN sputtering are repeated every predetermined number of sheets.

By processing as above, the second reaction chamber (16)
The following effects can be obtained. That is, in the second reaction chamber (16), TiH is deposited on the surface of the target (9) by continuing the film forming process by the phytoturn process.
foreign matter begins to form. However, by performing the left turn process, the second reaction chamber (1
In step 6), T1 sputtering is performed, so the TIN formed on the surface of the target (9) is blown away together with T1.
Silicon wafer (12) It is incorporated into the T1 film formed on the surface. This is called the cleaning effect of T1 sputtering. Further, the cleaning effect similarly occurs in the first reaction chamber (6). Figure 2 shows
This is an example showing the cleaning effect of Ti sputtering. In Figure 171-, the horizontal axis K shows the number of processed silicon wafers when films were formed in the same reaction chamber in the order of TiN reactive sputtering, T1 sputtering, and TiN reactive sputtering, and the vertical axis shows the number of foreign particles generated on busy silicon wafers. It shows the progress. In this way, the number of foreign particles increased by TiN reactive sputtering can be reduced by the cleaning effect of Ti sputtering. In addition, even if KTiN reactive sputtering is performed after the cleaning effect of
The number of foreign objects does not increase.

In Figure 2, Tie i reactive sputtering is performed until the number of foreign particles increases to an extreme extent, but if the cleaning effect is performed before the number of foreign particles increases dramatically, The number of foreign objects can always be kept below a certain level.

However, even if the cleaning effect is performed, there is almost no effect on the reliability of the film quality due to the incorporation of TiN into the 'I'i thin film (30). The reason is as follows. First, because the right turn process and the left turn process are repeated in a short period of time, the TiN formed on the surface of the target (9) is blown off by the cleaning effect while it is relatively small, so the absolute amount of TiH can be reduced. be. In addition, T1 sputtering is performed using Ti
This is because the film formation efficiency is higher than that of N reactive sputtering, and the film is formed in a short time, so there is less TII adhesion per V recon wafer.

As described above, the target (9) contaminated by TiN reactive sputtering is always cleaned by performing T1 sputtering. For this reason, Ti
The number of foreign particles generated by e ff reactive sputtering is always suppressed to a certain number or less, making it possible to form a high quality barrier layer (27). Therefore, such a barrier layer (
27) to form a semiconductor device, it has the effect of providing excellent characteristics and high reliability.

Here, the number of sheets to be processed is set to 25 for each turn of the fit-turn process and the left-turn process, but it may be set to less than that. In addition, although both the right-turn process and the left-turn process are performed alternately here, in order to form a thin film without generating a large amount of foreign matter, it is not necessary to perform them alternately, and the processing direction can be controlled as appropriate. It may also be treated as such, producing the same effect as above.

[Effect of the invention J As described above, the invention F! According to AK, when forming a barrier layer using a multi-chamber type sputtering device, it is possible to always suppress the number of foreign particles generated during Tie reactive sputtering to a certain number or less, and a highly reliable barrier. It is possible to easily obtain layers.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram of a multi-chamber sputtering apparatus which is an embodiment of the present invention, the t/g2 diagram is for explaining the cleaning effect of T1 sputtering, and Fig. 3 is a conventional multi-chamber sputtering apparatus. Figure 4 shows the T1 thin film TiNx N Ml and 2
Figures 5 to 7 are diagrams schematically showing the reaction mechanism of TiN reactive sputtering, and Figure 8 is a diagram showing the structure of a main part of a semiconductor device to which a barrier layer having an M structure is applied.
FIG. 3 is a diagram showing the number of foreign particles generated on a silicon wafer during film formation by reactive sputtering. In the figure, α) is the 10th draw chamber, and (6) is the 1st draw chamber.
reaction chamber, (7) is the cathode, (8) is the anode, (12) is the V recon wafer% (14) is the vacuum valve for introducing Ar gas, (
16) is the second reactivity, (17) is the vacuum valve for introducing town gas, (19) is the 20th drop chamber, (23) is the silicon wafer with T1 film, (24) is the silicon with TiNX/Ti Wafer, (27) is barrier layer, (28) is T1
The thin film (29) is a TiNx1 film, and the (32) is a substrate. Note that the same reference numerals in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] (1) A first reaction chamber having parallel plate electrodes and into which a gas to generate plasma and a nitrogen gas contributing to a film formation reaction to be formed on a substrate to be processed can be introduced; A second reaction chamber is arranged adjacent to the first reaction chamber, and a preliminary chamber is provided in one of each of the first reaction chamber and the second reaction chamber, which can be evacuated, and in which the substrate is carried in and out. A thin film forming apparatus that can transfer bidirectionally from one preparatory chamber to another preparatory chamber, and performs film formation by transferring from one direction or the opposite direction.