JPH0730088A - Manufacture of solid-state image sensing device - Google Patents

Abstract

PURPOSE:To make it possible to shorten significantly the manufacturing process of a solid-state image sensing device by a method wherein a barrier metal layer inn the connection part of a peripheral circuit part and antireflection film under a light-shielding film in an imaging element part are shared by the same one film. CONSTITUTION:An antireflection and barrier metal film 35 is formed on an insulating film 16 of an imaging element part 21 and an insulating film 25 of a peripheral circuit part 22. Then, a metal layer 36 for forming an alloy layer with a semiconductor substrate 31 in the connection part of the circuit part 22 is formed on the layer 35. Then, the layer 36 is diffused in the layer 35 and a heat treatment for forming a metal-semiconductor alloy layer 38 at the connection part is performed on the connection part. Whereby, a good ohmic contact is obtained by the layer 38 and a barrier metal layer 28 (35) at the connection part of the circuit part 22. Simultaneously with that, an antireflection film 19 (35) is formed in the element part 21 and a reduction in the manufacturing process of a solid-state image sensing device is attained.

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 solid-state image pickup device.

[0002]

2. Description of the Related Art FIG. 7 shows an example of an image pickup element portion of a conventional CCD solid-state image pickup device 1. This CCD solid-state imaging device 1
The first second type on the silicon substrate 2 of the first conductivity type, for example, N type
In the conductivity type or P type well region 3, an N type impurity diffusion region 4 forming a light receiving portion 10, an N type transfer channel region 5 forming a vertical transfer register 12, and a P type channel stop region 6 are formed. The N-type impurity diffusion region 4
A P-type positive charge storage region 7 is formed on the upper side, and a second P-type well region 8 is formed immediately below the N-type transfer channel region 5, respectively.

Here, a photodiode PD is formed by the PN junction j of the N type impurity diffusion region 4 and the P type well region 3.
The light receiving unit (photoelectric conversion unit) 10 is configured by. The light receiving unit 10 is provided corresponding to each pixel.

Then, a transfer electrode 15 made of polycrystalline silicon is formed on the transfer channel region 5, the channel stop region 6 and the read gate portion 11 which constitute the vertical transfer register 12 via a gate insulating film 14 such as a SiO ₂ film. Thus, the transfer channel region 5, the gate insulating film 14, and the transfer electrode 15 form a vertical transfer register 12.

An interlayer insulating film 16 made of, for example, PSG (phosphorus silicate glass) is laminated on the entire surface including the transfer electrode 15 and the positive charge accumulation region 7, and the region including the transfer electrode 15 is further excluded except the light receiving portion 10. A light-shielding film, for example, an Al light-shielding film 17 is selectively formed on the interlayer insulating film 16.

The Al light-shielding film 17 is directly provided from the light receiving portion 10
In order to block light that is incident on the vertical transfer register 12 (light that is obliquely incident), a protruding portion 17a that is partially extended to the light receiving unit 10 side is integrally provided. And this A
A surface protection layer 18 of, for example, a plasma SiN film is formed on the entire surface including the light shielding film 17.

[0007]

By the way, the conventional CC
In the D solid-state imaging device 1, as shown in FIG. 7, when the light L ₀ is incident on the light receiving unit 10, a part L ₁ of the incident light L _{0 and} the protrusion 17a of the Al light-shielding film 17 and the silicon. Insulating film between regions (gate insulating film 14 and interlayer insulating film 1
6) The inside is multiply reflected and leaks into the vertical transfer register 12, and charges are generated by photoelectric conversion. This charge is CC
This causes smear in the D solid-state imaging device.

In order to reduce the smear caused by the multiple reflection, for example, as shown in FIG. 4, a thin film such as a TiON film or a TiN film having a low reflectance, that is, a so-called reflection is formed under the Al light shielding film 17. A method of forming the prevention film 19 has been considered. The antireflection film 19 is formed of the interlayer insulating film 16
Low reflectance at the interface is required.

On the other hand, in the peripheral circuit section 22 provided in the periphery of the image pickup element section 21 of the CCD solid-state image pickup device 1, for example, an N type diffusion region 24 formed in the P type well region 3 is covered with SiO ₂ or the like. Contact hole 26 in insulating film 25
The Al wiring 27 is ohmic-contacted through.

This diffusion region (silicon region) 24 and Al
In connection with the wiring 27, a barrier metal layer 28 is formed in order to prevent leakage current due to alloy spikes and increase in contact resistance due to silicon deposition and to realize good ohmic contact. For the barrier metal layer 28, for example, a thin film of titanium nitride (TiN) / pure titanium (Ti) laminated structure is used. That is,
A pure titanium layer for forming a titanium silicide layer 29 that obtains a good ohmic contact with the diffusion region 24, and an alloy spike in which Al is introduced into silicon and a silicon deposition (Al wiring) are formed continuously on the pure titanium layer. The barrier metal layer 28 is formed by a two-layer structure of a titanium nitride layer having a barrier property against silicon that is contained at about 1% in epitaxial growth on the silicon region and increases the contact resistance).

In order to form the antireflection film 19 and the barrier metal layer 28 having different purposes in the same solid-state image pickup device, the manufacturing method shown in FIGS. 5 and 6 is usually employed.

First, as shown in FIG. 5A, the image pickup device portion 21 on the silicon substrate 31 in which the regions shown in FIG. 4 are formed.
The gate insulating film 14, the transfer electrode 15 and the interlayer insulating film 16 are formed on the region corresponding to the above, the insulating film 25 such as SiO ₂ is formed on the region corresponding to the peripheral circuit portion 22, and the position corresponding to the diffusion region is formed. A contact hole 26 is formed in.

Next, as shown in FIG. 5B, the peripheral circuit section 2
A barrier metal layer 28 having a two-layer structure of a pure titanium layer 32 and a titanium nitride layer 33 is formed on the entire surface of the region corresponding to 2 and the image pickup device portion 21.

Next, as shown in FIG. 5C, a barrier metal layer other than the peripheral circuit portion 22, that is, the barrier metal layer 28 on the side of the image pickup device portion 21 is formed by using a photoetching technique.
Are selectively removed by etching.

Next, as shown in FIG. 6D, after forming an antireflection film 19, for example, a titanium nitride (TiN) thin film on the entire surface, as shown in FIG. 6E, the antireflection film 19 except for the image pickup device portion 21. Are also selectively removed by the photo-etching technique.

Thereafter, as shown in FIG. 6F, an Al vapor deposition film is formed and patterned to form an Al light shielding film 17 and an Al wiring 27.

At the connection portion in the contact hole 26, a titanium silicide layer 29 is formed by mutual diffusion between the pure titanium layer 32 and the silicon substrate 31 by heat treatment.

As described above, the antireflection film 17 having different purposes is used.
To form the barrier metal layer 28 and the barrier metal layer 28, it is necessary to use a two-step forming method in which the barrier metal layer 28 and the barrier metal layer 28 are individually formed, which inevitably complicates the manufacturing process.

In view of the above points, the present invention provides a method of manufacturing a solid-state image pickup device, which enables reduction of the number of steps, cost reduction, and improvement of manufacturing yield.

[0020]

According to the present invention, an image pickup device section 2 is provided.
1 and the peripheral circuit section 22, and the light-shielding film 1 of the imaging element section 21.
In the method for manufacturing a solid-state image pickup device, in which the antireflection film 19 is provided under 7 and the barrier metal layer 28 is provided in the connection portion of the peripheral circuit unit 22, the image pickup device unit 21 and the peripheral circuit unit 22 are provided.
On the insulating films 16 and 25 of FIG.
And the metal layer 3 on which the semiconductor substrate 31 of the connection portion and the alloy layer are to be formed on the antireflection / barrier metal layer 35.
6 and a heat treatment step for diffusing the metal 36 in the antireflection / barrier metal layer 35 to form a metal / semiconductor alloy layer 38 at the connection portion.

It is preferable that the antireflection / barrier metal layer 35 is made of titanium nitrite or titanium oxynitride, and the metal layer 36 is made of titanium.

[0022]

In the present invention, the antireflection / barrier metal layer 35 is formed on the insulating films 16 and 25 of the image pickup device section 21 and the peripheral circuit section 22, and the metal is formed on the antireflection / barrier metal layer 35. After the layer 36 is formed, by heat treatment, the metal layer 36 diffuses in the antireflection / barrier metal layer 35, and the metal / semiconductor alloy layer 38 is formed at the connection portion of the peripheral circuit portion 22. Therefore, in the connection portion of the peripheral circuit portion 22, the metal / semiconductor alloy layer 38 and the barrier metal layer 2
8 (35), a good ohmic contact can be obtained, and at the same time, the antireflection film 19 (3
5) is formed, and the reduction of the manufacturing process is achieved.

Titanium nitride or titanium oxynitride is used as the antireflection and barrier metal layer 35,
When titanium is used as the metal layer 36, the peripheral circuit section 2
A good barrier metal layer 28 can be formed in the first connection portion, and a good antireflection film (a film having a so-called low reflectance characteristic) 19 can be formed in the image pickup device portion 21.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a method for manufacturing a solid-state image pickup device according to the present invention will be described below with reference to FIGS.

1 and 2, parts corresponding to those in the above-mentioned FIG.

FIG. 3 shows the multi-chamber type D.C. used in this embodiment. The C magnetron sputtering apparatus 41 is shown. This D. C magnetron sputtering device 41
Is attached to a separation chamber 42 which is evacuated in the center, a plurality of sputtering treatment chambers arranged around it, that is, a first sputtering treatment chamber 44 to which at least a pure Ti target 43 is attached, and a TiN or TiON target 45. Second sputter processing chamber 46 and Al-1
The substrate to be sputtered is exposed to the atmosphere by the transfer robot 50 that has the third sputtering processing chamber 48 to which the% Si target 47 is attached and the preliminary exhaust chamber 49, and is installed in the separation chamber 42. It is configured to be transported to each of the sputtering processing chambers 46, 44, 47 without being involved.

In the present embodiment, first, as shown in FIG. 1A, although the internal structure is omitted, the image pickup device portion 21 on the silicon substrate 31 in which the respective regions similar to those in FIG. 4 described above are formed.
Gate insulating film 1 made of SiO ₂ film, etc. in the region corresponding to
4. A transfer electrode 15 made of polycrystalline silicon and an interlayer insulating film 16 made of PSG are formed, and an insulating film such as SiO ₂ (for example, the interlayer insulating film 1 is formed in a region corresponding to the peripheral circuit portion 22).
The same film as 6 may be used) 25 to form the silicon substrate 3
A contact hole 26 is formed at a position corresponding to the connection portion of the first diffusion region.

Each region in the silicon substrate 31, the gate insulating film 14, the transfer electrode 15, the insulating film 25, and the contact hole 26 can be formed by a usual method.

Next, the base 31 is treated with D.I. The TiN film having a thickness of, for example, about 70 nm is transferred to the second sputtering processing chamber 46 of the C magnetron sputtering apparatus 41 and is deposited on the entire surface of the insulating film 25 including the interlayer insulating film 16 and the contact hole 26 as shown in FIG. 1B. Alternatively, an antireflection and barrier metal layer 35 such as a TiON film is formed.

For example, the conditions for forming the TiN film are as follows: mixed gas pressure of argon and nitrogen is 8 mTorr and sputtering power is 3
KW and sputter time are 71 sec.

Next, the substrate 31 is transferred from the second sputtering processing chamber 46 to the first sputtering processing chamber 44 in a vacuum state, and as shown in FIG. 2C, the antireflection / barrier metal layer 3 is formed.
A pure Ti layer 36 having a thickness of about 30 nm is formed on the film 5. The conditions at this time are that the argon gas pressure is 4 mTorr, the sputtering power is 2 kW, and the sputtering time is 15 sec.

By this operation, the pure titanium layer 36 and the TiN layer are
Alternatively, a laminated film 37 is formed by the TiON anti-reflection and barrier metal layer 35.

Next, the base 31 on which the laminated film 37 is formed
Is subjected to heat treatment at 450 ° C. for 30 minutes in a nitrogen atmosphere. By this heat treatment, as shown in FIG. 2D, the antireflection / barrier metal layer, that is, pure Ti 36 on the TiN or TiON film 35 is diffused in the TiN or TiON film 35,
The titanium silicide layer 38 is formed by reacting with the silicon of the base 31 at the connection portion in the contact hole 26.

Similarly, pure Ti is also used on the side of the image pickup device 21.
36 diffuses into the TiN or TiON film 35, but there is no formation of a silicide layer at the interface with the interlayer insulating film 16,
There is no change in the reflectance of the N or TiON film 35.

Next, the substrate 31 is treated with D. The third sputtering processing chamber 48 of the C magnetron sputtering device 41
Then, an aluminum thin film serving as a light-shielding film and a wiring is formed on the TiN or TiON film 35, and then the aluminum thin film and the TiN or TiON film 35 are patterned into a desired pattern by using a photoetching technique.

As a result, as shown in FIG. 2E, the Al light-shielding film 17 is formed in the image pickup device portion 21, and the antireflection film 19 of TiN or TiON is formed under the Al light-shielding film 17, and the peripheral circuit portion is formed. In FIG. 22, the titanium silicide layer 38 is formed in the connection portion in the contact hole 26.
Via a TiN or TiON barrier metal layer 28
Is formed, and the Al wiring 27 is formed on the barrier metal layer 28.
Is formed.

In the solid-state imaging device 39 thus obtained, the titanium silicide layer 38 is formed only at the Si interface below the barrier metal layer 28 of TiN or TiON at the connection portion of the peripheral circuit portion 22, so that the silicon substrate is formed. 31
And a good ohmic contact with the diffusion region of the same, and at the same time, the antireflection film 19 made of TiN or TiON film is formed under the light shielding film 17 of the image pickup device section 21 to reduce the smear caused by the leaked light. It

According to the above embodiment, the barrier metal layer 2
8 and the antireflection film 19 are combined into one thin film 35, the number of manufacturing steps of the solid-state imaging device can be significantly reduced, the cost can be reduced, and the yield can be improved.

The heat treatment after forming the laminated film 37 of the anti-reflection / barrier metal layer 35 of the TiN or TiON film and the pure titanium layer 36 is performed by D. It can also be achieved by heating the lamp in another processing chamber of the C magnetron sputtering apparatus 41.

In the above heat treatment, the coverage of contact holes is improved by performing Al sputtering at a high temperature, but heating at this time can be used instead.

The antireflection / barrier metal layer 35 is made of TiN, T or T if it is a film having a low reflectance and a barrier property.
Materials other than iON can also be applied. Further, the metal layer 36 on the antireflection / barrier metal layer 35 is also made of a material other than pure titanium as long as it diffuses in the layer 35 without impairing the characteristics of the layer 35 and makes an alloy with silicon to obtain a good ohmic contact. It can be applied to metal.

[0042]

According to the present invention, the barrier metal layer in the connection portion of the peripheral circuit portion and the antireflection film under the light-shielding film in the image pickup element portion are made to serve as one and the same film. The manufacturing process can be significantly shortened, and the cost can be reduced and the yield can be improved.

[Brief description of drawings]

FIG. 1A is a manufacturing process diagram of an embodiment according to the present invention. B is a manufacturing process diagram of an example according to the present invention. FIG.

FIG. 2C is a manufacturing process diagram of an example according to the present invention. D is a manufacturing process diagram of an example according to the present invention. E is a manufacturing process diagram of an example according to the present invention.

FIG. 3 shows a multi-chamber type D. It is a block diagram of a C magnetron sputtering apparatus.

FIG. 4 is a sectional view of a CCD solid-state imaging device applied to the present invention.

FIG. 5 is a manufacturing process diagram of A reference example. It is a manufacturing-process figure of B reference example. It is a manufacturing-process figure of C reference example.

FIG. 6 is a manufacturing process diagram of D reference example. It is a manufacturing-process figure of E reference example. It is a manufacturing-process figure of F reference example.

FIG. 7 is a cross-sectional view of an image pickup element portion of a CCD solid-state image pickup device according to a conventional example.

[Explanation of symbols]

1, 39 Solid-state imaging device 2 Silicon substrate 3 First well region 4 Impurity diffusion region 5 Transfer channel region 6 Channel stop region 7 Positive charge storage region 8 Second well region 10 Light receiving part 11 Read gate part 12 Vertical transfer register 14 Gate insulating film 15 Transfer electrode 16 Interlayer insulating film 17 Light-shielding film 17a Projection part 18 Surface protective film 19 Antireflection film 21 Imaging device part 22 Peripheral circuit part 24 Diffusion region 25 Insulation film 26 Contact hole 27 Wiring 28 Barrier metal layer 29 Titanium Silicide layer 31 Silicon substrate 32 Pure titanium film 33 TiN film 35 Antireflection and barrier metal layer (TiN or TiO 2)
N) 36 Pure titanium layer 37 Laminated film 41 Multi-chamber system D.I. C magnetron sputtering equipment

Claims (2)

[Claims] 1. A solid-state imaging device comprising an image pickup device section and a peripheral circuit section, an antireflection film being provided under a light-shielding film of the image pickup element section, and a barrier metal layer being provided at a connection section of the peripheral circuit section. In the manufacturing method, a step of forming an antireflection / barrier metal layer on an insulating film of the image pickup device section and the peripheral circuit section; and a semiconductor substrate and an alloy layer of the connection section on the antireflection / barrier metal layer. And a heat treatment step for diffusing the metal in the antireflection / barrier metal layer to form a metal / semiconductor alloy layer in the connection portion. Solid-state image pickup device manufacturing method. 2. The method for manufacturing a solid-state imaging device according to claim 1, wherein the antireflection / barrier metal layer is formed of titanium nitride or titanium oxynitride, and the metal layer is formed of titanium. .