JPH0629295A - Semiconductor device - Google Patents

Abstract

(57) [Summary] [Structure] The semiconductor device of the present invention comprises a semiconductor body (1) having a surface (4) provided with an insulating layer (6), and a contact window (7) is provided in the insulating layer. A silicon region (3,5) located below the insulating layer through the contact window is formed of TiN containing 10 to 30 atomic% Ti provided on the insulating layer and in the contact window. Barrier layer (8), Intermediate layer for improving barrier properties (9)
And a semiconductor device connected to a conductor pattern (11) comprising a composite layer (8, 9, 10) including an aluminum upper layer (10). In the present invention, the barrier property improving intermediate layer (9) is a TiW layer containing nitrogen. The composite layer of the TiW barrier layer (8) and the nitrogen-containing TiW intermediate layer (9) exhibits better barrier properties than the TiW barrier layer exposed to air.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a semiconductor body having a surface provided with an insulating layer, a contact window being provided in the insulating layer, and a silicon layer located below the insulating layer through the contact window. A region, a barrier layer of TiW containing 10 to 30 atomic% Ti provided on the insulating layer and in the contact window;
The present invention relates to a semiconductor device connected to a conductor pattern composed of a composite layer including a barrier property improving intermediate layer and an aluminum upper layer.

[0002]

The insulating layer is, for example, a layer of silicon oxide, silicon nitride or silicon oxynitride. The silicon region located below the insulating layer can be a region of single crystal silicon or polycrystalline silicon. A metal silicide upper layer may be further provided in these regions. A single crystal region is a semiconductor region provided in a semiconductor body, such as the source and drain regions of a field effect transistor. The polycrystalline regions are the contact regions of the conductor tracks provided on the surface, for example the gate electrode of a field effect transistor, which regions consist of highly doped conductive polycrystalline silicon. The aluminum top layer can consist of pure aluminum, but it can also consist of aluminum with up to a few% of silicon or copper added.

In the manufacture of semiconductor devices, a barrier layer of TiW is used between the silicon and aluminum conductor tracks to prevent the reaction between silicon and aluminum. This reaction can occur during the process in which the semiconductor body is heated to relatively high temperatures several times during the manufacture of semiconductor devices.

It has been determined that the TiW barrier layer does not actually form a complete barrier. Ti and W from this barrier layer form a compound with aluminum. Although a compound with titanium is more likely to form than a compound with tungsten, and therefore, a barrier layer that does not contain titanium is actually preferred, although in practice 10-30 atomic% titanium is added to the barrier layer. This is done so that this layer has good adhesion to the underlying substrate and that this layer forms a low ohmic contact with the underlying silicon or metal silicide. However, this is also done so that this layer can be deposited by practical sputter deposition methods.

During the sputter deposition process, a slice of semiconductor material is placed in the reaction chamber, facing a target of the material to be deposited, and then argon is introduced into the reaction chamber to generate a plasma near the target. Ions from the plasma strike the target, ejecting atoms from the target, a portion of which reaches the slice and forms a layer on the slice. In the subsequent manufacturing process of the semiconductor device, this slice is subdivided into a large number of semiconductor bodies. During the sputter deposition process, the atoms released from the target reach not only the slice but also the components of the reaction chamber near the slice. Therefore, it is also deposited on these components of the reaction chamber. Repeating the sputter deposition process to deposit layers on other slices increases the thickness of the layers on the components of the reaction chamber. When depositing pure tungsten, a poorly adherent layer forms on the components of the reaction chamber. When the layer of pure tungsten on the components of the reaction chamber is about 20 μm thick, particles or particles of tungsten can come off from this layer and deposit on the surface of the slices that are now present in the reaction chamber. Such relatively large pieces are undesirable. For this reason, it is necessary to clean the reaction chamber before the layers on the components of the reaction chamber reach this critical thickness. Addition of 30 atomic% titanium to this layer shows good adhesion to the reaction chamber components and does not actually flake off to a thickness of about 300 μm. This means that the reaction chamber does not need to be frequently cleaned, which is very advantageous in practice.

US Pat. No. 5,019,234 discloses a semiconductor device of the type mentioned in the introduction, in which a barrier property improving intermediate layer, a TiW barrier layer and an aluminum layer are deposited for a period of time before deposition. Formed by exposing to air.

[0007]

The use of such known barrier property-improving intermediate layers has the disadvantage that it takes several days to obtain a practical level of improvement in the barrier properties upon exposure to air.
As a result, the manufacturing time of the semiconductor device actually increases by several days. Furthermore, exposure to air also has the disadvantage that the deposition of the barrier layer and the aluminum layer to be deposited thereon cannot be carried out in modern multichamber deposition equipment. In such a deposition apparatus, a semiconductor slice is transferred under low pressure from one deposition chamber to another deposition chamber, and one layer is deposited in each chamber.
Occasionally, for example, additional chambers are also provided for carrying out etching processes. In such a device, for example, the surface of the slice can be first cleaned by etching, then a barrier layer of TiW can be deposited, and finally a layer of aluminum can be deposited without breaking the vacuum of the device. The object of the invention is to overcome the above-mentioned drawbacks.

[0008]

The present invention is characterized in that, in a semiconductor device of the type described in the introduction, the barrier property improving intermediate layer is a TiW layer containing nitrogen. The intermediate layer of TiW containing nitrogen (hereinafter abbreviated as TiWN) is deposited by a normal sputter deposition process by generating plasma in argon containing nitrogen in the same deposition chamber immediately after the deposition of TiW. can do. This process practically does not increase the manufacturing time of the device and also allows the deposition of the composite layer to form the conductor pattern to be carried out in a multi-chamber deposition device.

It has been determined that TiW barrier layers in combination with a TiWN interlayer for improved barrier properties exhibit better barrier properties than barrier layers of TiW exposed to air. This was confirmed by the experimental results of depositing these layers on the several silicon slices provided with the silicon oxide layer in the multi-chamber deposition apparatus described above. A layer of TiW, a layer of TiWN and a layer of aluminum were deposited in this order on some slices without breaking vacuum. These slices were compared to slices where a known TiW barrier was deposited and exposed to air prior to deposition of an aluminum layer. In this experiment, these silicon slices were heated in vacuum to a temperature of 450 ° C. for some time after deposition of aluminum. The sheet resistance of the aluminum layer was measured during this heating. Since the compounds formed by the reaction of titanium and tungsten with aluminum have a higher resistance than that of aluminum, the measured resistance increases as the aluminum is consumed to form these compounds. This aluminum consumption is significantly lower when using the combination of barrier layer and intermediate layer according to the invention than when using the known barrier layers which have been exposed to air for a long period of time, in the case of the former. It was confirmed that the upper aluminum could hardly react with Ti and W. Such a reaction is at 450 ℃
During the heat treatment, the formation of a 1 to 3 nm layer containing Al and N at the interface between the TiWN layer and the aluminum layer is prevented. This layer containing Al and N constitutes a barrier to the reaction and makes the adhesion of aluminum to the TiWN intermediate layer very good. Since the layer containing Al and N is extremely thin and the amount of aluminum consumed for forming this layer is very small, the resistance value of the aluminum layer hardly increases.

Depositing an aluminum layer on the barrier property improving interlayer of TiWN containing 15-40 atomic% nitrogen results in significantly less aluminum consumption than using a TiW barrier layer exposed to air. 30-40 atom% N
It is preferred to use an intermediate layer of TiWN containing In this case, the aluminum consumption is extremely low. 40
A TiWN layer containing more than atomic%, eg 50 atomic% N, is not preferred as an intermediate layer due to the evolution of nitrogen from this layer during subsequent heat treatments. This nitrogen emission degrades the adhesion between the aluminum layer deposited on the intermediate layer and the intermediate layer. Such delamination is not observed when using a TiWN layer containing 40 atomic% or less N.

It was confirmed that the combination of the TiW barrier layer and the TiWN intermediate layer for improving the barrier property according to the present invention not only has the good barrier property described above, but also has the advantage of enabling a practical sputter deposition process. Was given. For a practical sputter process, as stated above, the layers deposited on the components near the semiconductor slice in the reaction chamber should have good adhesion to each other and to these components. is important. The ability to prevent stripping of small pieces from this layer during the deposition process until the layer deposited on these components is thicker eliminates the need for frequent cleaning of the deposition apparatus. TiW adheres well to these components in the reaction chamber. In addition, TiW adheres well to each other to TiW and TiWN layers deposited successively on these components. In the absence of the TiW layer, the TiWN layer itself forms a satisfactory barrier between silicon and aluminum, but does not provide the desired adherence to the reaction chamber components. In this case, the TiWN layer starts to peel off from the constituent elements of the reaction chamber with a thickness of 5 μm or less. The materials from which the components of the reaction chamber are manufactured play practically no important role. Such poor adhesion is also seen when using aluminum. This is because the constituent elements of the reaction chamber do not reach a high temperature such as 450 ° C., so that the above-described compound containing Al and N, which strongly improves the adhesion between the Al layer and the TiWN layer, is not formed.

The thickness of the TiW barrier layer is preferably 2 to 5 times the thickness of the intermediate layer for improving barrier properties. In this case, undesired stripping of the particles of this layer does not occur until a layer having a thickness of about 300 μm is deposited on the components of the reaction chamber. In particular, it is preferable that the TiW barrier layer has a thickness of 60 to 100 nm and the intermediate layer for improving barrier properties has a thickness of 10 to 30 nm. In this case, the TiW barrier layer according to the invention and the TiW
The barrier properties of the combination with the N interlayer are optimized and these layers are practically easy to deposit.

[0013]

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be described in more detail with reference to the drawings on the basis of several exemplary embodiments. 1 to 3 show some fabrications of semiconductor devices in which a field oxide region 2 and a p-type semiconductor region 3 adjoining a surface 4 are provided in a conventional manner in a semiconductor body 1 of n-type single crystal silicon, for example. The process is shown. A conductor track 5 of polycrystalline silicon is provided on the surface 4. Next, the surface 4 is provided with an insulating layer 6 of, for example, silicon oxide, silicon nitride or silicon oxynitride. The insulating layer 6 is provided with a contact forming window 7 in the silicon region located therebelow. These silicon regions may be regions of single crystal silicon such as the semiconductor region 3 or regions of polycrystalline silicon, and these regions may or may not be provided with an upper layer of metal silicide. Figures 1-3
Shows only the contact window 7 exposing the semiconductor region 3,
It is obvious that the conductor 5 can be exposed by such a contact window.

Next, a TiW barrier layer 8 containing 10 to 30 atomic% Ti, an intermediate layer 9 for improving barrier properties, and an aluminum upper layer.
Composite layers 8, 9, 10 comprising 10 on insulating layer 6 and contact window 7
Provide inside. The top layer 10 may be pure aluminum, but a few percent of silicon and copper may be added to this layer.

In the present invention, the barrier property improving intermediate layer 9 is a TiW layer containing nitrogen. The intermediate layer of TiW containing nitrogen (hereinafter abbreviated as TiWN) is formed by a normal sputter deposition process by adding nitrogen to argon and generating plasma in the same deposition chamber immediately after the deposition of the TiW layer. Can be deposited. This process does not substantially increase the manufacturing time of the device and allows the deposition of the composite layers 8, 9, 10 to form the conductor pattern 11 to be carried out in a multi-chamber deposition device. Furthermore, Ti for improving barrier properties
It has been found that the TiW barrier layer 8 in combination with the WN intermediate layer 9 exhibits better barrier properties than the barrier layer of TiW exposed to air.

After the conductor pattern 11 connected to the semiconductor region 3 through the contact window 7 is etched into the composite layers 8, 9, 10 the composite layers of the insulating layers 12, 13, 14 are provided. A layer 12 of silicon oxide is first provided by plasma deposition (PECVD), then a layer 13 of spin-on glass (SOG) is provided by spin-on, and finally a layer 14 of silicon oxide is again provided by plasma deposition. Contact windows on the composite layers 12, 13 and 14
15 is provided so that the conductor pattern 16 provided on the composite layer is in contact with the aluminum upper layer 10. Composite layer 12,
Surface smoothing is obtained by using a layer 13 of spin-on glass in 13, 14 so that the upper silicon oxide layer 14 is fairly planar.

The TiW barrier layer 8 and the intermediate layer 11 ensure that the aluminum layer 10 adheres well to the insulating layer 6.
And to prevent the interaction between the silicon of the semiconductor region 3 and the aluminum of the aluminum layer 10 of the conductor tracks 11 provided on its surface. Such interactions may occur during subsequent manufacturing of the semiconductor device, during which the semiconductor body is heated to relatively high temperatures several times or more. During the deposition of the silicon oxide layer 12, the semiconductor body 1 is exposed to 300 ° C.
Heated for about 40 minutes and then at 425 ° C. for about 40 minutes to impregnate the spin-on-glass layer 13 after deposition of this layer,
It is then heated again to 300 ° C. for about 10 minutes during the deposition of the silicon oxide layer 14. Furthermore, after providing the conductor pattern 15 (the semiconductor body 1 reaches a temperature of about 200 ° C. during this process), additional silicon oxide and silicon nitride layers are usually deposited (both layers not shown). During these deposition processes, the semiconductor body 1 is heated to 300 ° C. for about 30 minutes. Finally,
The final heat treatment is carried out at a temperature of 425 ° C for about 20 minutes. In fact, aluminum does not react with Ti and W from the barrier layer at temperatures below 300 ° C, and this reaction occurs mainly during heat treatment above 400 ° C. Therefore, only heat treatments above 400 ° C., in this example at a temperature of 425 ° C. for a total of 60 minutes, are of practical importance for this chemical reaction.

FIG. 4 is a schematic diagram of a multi-chamber deposition apparatus suitable for depositing composite layers 8, 9, 10.
The device comprises an airtight housing 20 in which four chambers 21, 22, 23, 24 are arranged in this example.
The semiconductor slices can be transferred from one chamber to another under vacuum in the housing 20 as indicated by the arrow. The semiconductor slice can be inserted into and removed from the housing 20 via the first chamber 21 (so-called load lock). In the second chamber 22, for example, the slice is subjected to a normal sputter etching process to clean the slice surface. The barrier layer 8 and the intermediate layer 9 are deposited in the third chamber 23, and the aluminum layer 10 is deposited in the fourth chamber 24. Finally, the slice is taken out of the chamber 20 again using the first chamber. At this time, the slice comprises a large number of semiconductor devices in the final step shown in FIG. In a subsequent manufacturing process of the semiconductor device, this slice is divided into a large number of individual semiconductor bodies 1.

FIG. 5 shows one of the deposition chambers of a multi-chamber deposition apparatus. The support 31 is placed in the reaction chamber 30 and the flat target 32
And parallel to the plane ground conductive ring 33 surrounding it. A ground screen 34 is provided around the support 31. A slice 35 of semiconductor material is placed on the support 31, after which argon is introduced into the reaction chamber. A conventional DC voltage source 36 is connected between the target 32 and the surrounding conductive ring 33 to generate a plasma at a voltage of 300-700V. This plasma is confined in a space 37 between the target 32 and the slice 32 near the target 32 by a magnet 39 placed behind the target. Argon is gas inlet 38
Supply into the reaction chamber 30 from.

The magnet may rotate about axis 40. In effect, these magnets are rotated about the axis 40 several times per second during the deposition process to rotate the plasma and the space 37 in which the plasma is confined about the axis 40. This causes atoms to be knocked out uniformly from the entire surface of the target 32, resulting in uniform deposition on the front surface of the slice 35.

The slice 35 cools during deposition, during which the support
100 gas cushion 42 between 31 and semiconductor slice 35
Maintain at a pressure of ~ 2000Pa. Argon gas gas line 43
Through the support 31 and the slice 35. A rim 44 is provided on the support 31 and the slice 35 is pressed against this rim by a clamp (not shown). This makes the gas cushion 42
Limit the leakage of argon gas from the chamber to the reaction chamber 30. The support plate 31 is cooled by cooling water flowing from a pipe line 46 to a channel 45 provided in the support body 31.

The chamber 30 actually comprises a gas outlet 41, which can be connected to a pump (not shown) by means of which the gas can be discharged and the reaction chamber 30 maintained at the desired pressure.

In the experiments described below, several layers were deposited on several silicon slices provided with a silicon oxide layer with the multi-chamber deposition apparatus described above. about
80nm thick TiW layer, about 20nm thick TiWN layer and about 500nm
Thick aluminum layers were deposited in this order on several slices without breaking vacuum, these TiWN layers containing 35 atomic%, 20 atomic% and 10 atomic% N, respectively. Also, a TiW barrier layer about 100 nm thick was deposited on the other slices and the slices were exposed to air for a while before depositing an aluminum layer about 500 nm thick.

These layers were deposited in the reaction chamber described above. For depositing the TiW layer, 22 scc of argon per minute was introduced into the reaction chamber at a pressure of about 0.8 Pa and 4 KW of power was applied to the plasma. For the deposition of the TiWN layer,
0.8 scc of a mixture of 22 scc Argon and 12 scc Nitrogen per minute
It is introduced into the reaction chamber where the pressure is Pa and 1, 2 or 4 KW of electric power is applied to the plasma to generate 35 atom% and 20 atom% respectively.
And a TiWN layer containing 10 atomic% nitrogen was obtained. For the deposition of the aluminum layer, about 22 scc argon per minute
It was introduced into the reaction chamber at a pressure of 0.8 Pa and a power of 10 KW was applied to the plasma.

After deposition of the aluminum layer, all slices were heated in vacuum to about 450 ° C. for some time. The sheet resistance value of the aluminum layer was measured during this heating. The compounds resulting from the reaction of titanium and tungsten with aluminum have electrical resistance values significantly higher than the electrical resistance of aluminum, so that the measured resistance increases as aluminum is consumed for the formation of these compounds.

FIG. 6 shows the amount (thickness) of aluminum layers deposited on various barrier layers consumed during compound formation during heating at 450 ° C. (thickness) as a function of time.
Curves 50, 51 and 52 are 35 at%, 20 at% and 10 respectively.
3 shows the aluminum consumption of an aluminum layer deposited on a TiWN layer containing atomic% N. Curves 53 and 54 represent the aluminum consumption of the aluminum layer deposited on the TiW layer exposed to air for 60 minutes after deposition and the TiW layer exposed to air for several days after deposition, respectively.

As is apparent from the above, the amount of consumed aluminum depends on the TiW barrier layer 8 and the barrier property improving T according to the present invention.
There is significantly less use of the combination with the iWN interlayer 9 than known TiW barrier layers that have been exposed to air for extended periods of time. In the case of the present invention, aluminum is Ti and W
Hardly reacts with. Such a reaction may occur at the interface between the TiWN layer and the aluminum layer during heating at 450 ° C.
This is suppressed because a layer containing Al and N having a thickness of nm is formed. This layer forms a barrier to such reactions and allows the aluminum to adhere very well to the TiWN interlayer. Since this layer containing Al and N is very thin, the amount of aluminum consumed in forming this layer is very small, so that the resistance of the aluminum layer does not actually increase.

Significantly lower aluminum consumption than when using a TiW barrier layer exposed to the air
Is deposited on the TiWN intermediate layer 9 for improving barrier properties containing 15-40 atomic% nitrogen. 30-40 atom% N
It is preferred to use a TiWN intermediate layer 9 containing In this case, the aluminum consumption is extremely low. A TiWN layer containing 40 atomic% or more, for example 50 atomic% N, is not preferred as an intermediate layer due to the evolution of nitrogen from this layer during subsequent heat treatments. This deteriorates the adhesion between the aluminum layer deposited on the intermediate layer and the intermediate layer. No such delamination was observed when using a TiWN layer containing 40 atomic% or less N.

The combination of the TiW barrier layer 8 and the TiWN intermediate layer 9 for improving the barrier property according to the present invention has an advantage that not only the above-mentioned good barrier property but also a practical sputter deposition process is brought about. For a practical sputter deposition process, layers deposited on top of each other, such as the conductive ring 33 and the ground screen 34, which are located in the reaction chamber 30 near the slice 35, are stacked on top of each other. It is important to have good adhesion to 34 and 34. If a thick layer can be deposited on these components 33 and 34 without stripping the pieces from this layer, frequent cleaning of the deposition equipment is eliminated. It was confirmed that TiW has good adhesion to these components 33 and 34. Furthermore, TiW and TiWN layers deposited successively on these components have good mutual adhesion. TiWN without TiW layer
Although the layer alone forms a sufficient barrier between silicon and aluminum, it does not provide the desired adhesion to the reaction chamber components. In this case, the deposited layer on these components is 5
When the thickness is less than μm, it begins to fall off. These components of the reaction chamber are made of stainless steel or aluminum, for example. Poor adhesion also occurs when using aluminum. This is because these components in the reaction chamber do not reach a high temperature such as 450 ° C., so that the above-described Al and N-containing compound that strongly improves the adhesion between Al and TiWN is not formed.

The above-mentioned experiment was carried out for the TiW barrier layer 8 and the barrier property improving intermediate layer 9 having other thicknesses. From the results of this experiment, it was confirmed that the thickness of the TiW barrier layer 8 is preferably 2 to 5 times the thickness of the barrier property improving intermediate layer 9. In this case, a layer of approximately 300 μm thick can be formed on the components 33 and 34 by the time the undesired stripping off of this layer begins. In particular, T
The iW barrier layer 8 has a thickness of 60 to 100 nm, and the barrier property improving intermediate layer 9 has a thickness of 10 to 30 nm. In this case, the barrier properties of the combination of the TiW layer 8 and the TiWN layer 9 according to the invention are optimized and these layers can be deposited practically easily.

[Brief description of drawings]

FIG. 1 is a diagram showing one manufacturing process of a semiconductor device of the present invention.

FIG. 2 is a diagram showing a next manufacturing step of the semiconductor device of the present invention.

FIG. 3 is a diagram showing a next manufacturing step of the semiconductor device of the present invention.

FIG. 4 is a schematic view showing a multi-chamber deposition apparatus used for manufacturing the semiconductor device of the present invention.

5 shows one of the reaction chambers of the deposition apparatus shown in FIG.

FIG. 6 shows an aluminum layer deposited on various barrier layers.
3 is a graph showing the amount of aluminum consumed in the reaction with Ti and W during heating at 450 ° C. as a function of time.

[Explanation of symbols]

 1 Semiconductor Body 2 Field Oxide Region 3 Semiconductor Region 5 Conductor Track of Polycrystalline Silicon 6 Insulating Layer 7 Contact Window 8, 9, 10 Composite Layer 8 TiW Barrier Layer 9 TiWN Intermediate Layer 10 Aluminum Upper Layer 11 Conductor Pattern 12, 13, 14 Composite insulation 15 Contact window 16 Conductor pattern

 ─────────────────────────────────────────────────── ———————————————————————————————————————————————————————————————— Inventor Edwin Tibesswart The Netherlands 5621 Beer Eindowen Frünewach Wech 1

Claims (5)

[Claims] 1. A semiconductor body having a surface provided with an insulating layer, wherein a contact window is provided in the insulating layer, and a silicon region located under the insulating layer through the contact window is provided in the insulating layer. A semiconductor formed by connecting to a conductor pattern, which is provided on the top and in the contact window, of a TiW barrier layer containing 10 to 30 atomic% Ti, an intermediate layer for improving barrier properties, and a composite layer including an aluminum upper layer. In the device, the intermediate layer for improving barrier properties is a layer of TiW containing nitrogen, which is a semiconductor device. 2. The semiconductor device according to claim 1, wherein the barrier property improving intermediate layer contains 15 to 40 atomic% of nitrogen. 3. The semiconductor device according to claim 2, wherein the barrier property improving intermediate layer contains 30 to 40 atomic% of nitrogen. 4. The semiconductor device according to claim 2, wherein the TiW barrier layer has a thickness that is 2 to 5 times the thickness of the barrier property improving intermediate layer. 5. The semiconductor device according to claim 4, wherein the TiW barrier layer has a thickness of 60 to 100 nm, and the barrier property improving intermediate layer has a thickness of 10 to 30 nm.