JPH11204518A - Method and device for manufacturing semiconductor device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain uniformity of the film quality of a capacity film by supplying the oxidized gas formed in an oxidized-gas generating process to the surface of a substrate, which is heated to a specified temperature, and oxidizing material a be processed. SOLUTION: Oxygen is introduced into an ozone generator 22 from a gas inlet port 21. The oxygen gas is made to be a mixed gas of ozone and the oxygen by the ozone generator 22. The mixed gas is introduced into oxygen radical generator 24. The oxygen radical is generated in the oxygen radical generator 24 by the light which is irradiated from a low-pressure mercury lamp 23 provided in this oxygen-radical generator 24. The oxidized gas containing this oxygen radical is introduced into an oxidizing cell 26 from a gas inlet port 25. The single-layer stream of the oxidizing gas is made to flow on the substrate 29, and the capacity insulating film on a substrate 29 is oxidized. Thus, the uniformity of the film thickness of the capacity insulating film can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for manufacturing a semiconductor device for oxidizing an object to be processed on a substrate.
For example, the present invention relates to a method and an apparatus for oxidizing a capacitance insulating film such as Ta2O5.

[0002]

2. Description of the Related Art A capacitor insulating film such as Ta2O5 (tantalum oxide) has a high leak current density after being formed because the film contains many defects and impurities. In a film that is not subjected to heat treatment after film formation, a reaction with a metal electrode formed on the capacitor insulating film during the manufacturing process proceeds, and a leak current increases.

In the case of a Ta2O5 film, for example, 800
By performing the oxidation treatment at ℃, defects and impurity density in the film are reduced, and Ta2O5 is crystallized. As a result, a film with high stability is obtained, and defects and impurities are reduced, so that leakage current can be reduced. But,
When a Ta2O5 film is applied to a highly integrated semiconductor memory or the like, this oxidation treatment alone is not sufficient.

[0004] Therefore, oxygen plasma processing for generating oxygen plasma in a processing vessel while heating the substrate, and UVO for introducing ozone gas generated by an ozonizer into the processing vessel while heating the substrate and irradiating the substrate with ultraviolet light. ₍₃₎ There is a method of performing an oxidation treatment using an oxidation furnace after performing annealing or the like.

[0005]

However, in the case of the oxygen plasma treatment, oxygen ions are present together with oxygen radicals in the plasma, and these ions are accelerated by an electric field, and
Irradiated on 2O5 film. This has the effect of densifying the film if the energy is appropriate, but has the problem of damaging the film if the energy of the oxygen ions is too high.

In addition, even when the energy is appropriate, oxygen ions may not be generated when the stack has a three-dimensional structure and has a complicated shape with irregularities due to the rectilinearity of ions, or when the interval between the stack electrodes is narrow. There is a problem that an unirradiated region occurs, and the effect cannot be improved for the entire capacitance film on the stack electrode.

[0007] In the case of UVO ₃ annealing in which an O ₃ gas is introduced into a processing vessel and ultraviolet light is radiated, the irradiation intensity of light due to a light source in the substrate surface or the intensity of light due to the structure of the substrate. The irradiation intensity, that is, the number of photons per unit area is different, and the flow rate of active oxygen on the capacitance film is different in the substrate because the gas flow is random. The degree of progress of the oxidation is different, and uniformity of the film quality of the capacitance film cannot be obtained. Further, ultraviolet light to be irradiated directly on the substrate, for example if the SiO ₂ layer is present at the interface of Ta2O5 layer and stack the electrode in order to reach the light to the underlying Ta2O5, SiO ₂ layer at the interface Oxidation is also promoted,
There is a problem that the defect density increases as the thickness of this layer increases. Furthermore, the oxidation efficiency increases as the temperature of the substrate increases, but the lifetime of ozone sharply decreases as the temperature increases. For this reason, when the temperature of the wall surface of the processing container rises with the rise of the processing temperature, the ozone concentration drops sharply, and a sufficient effect cannot be obtained.

The present invention has been made in view of such a problem, and an object of the present invention is to deal with an object to be processed such as a capacitive insulating film formed on a stack electrode having a three-dimensional structure. Another object of the present invention is to provide an efficient semiconductor manufacturing method and apparatus which can uniformly act on an object to be processed with low damage and good uniformity.

[0009]

SUMMARY OF THE INVENTION The gist of the present invention is to provide a method of manufacturing a semiconductor device in which an object to be processed exposed on a substrate surface is oxidized by an oxidizing gas. An oxidizing gas generating step of irradiating light to generate an oxidizing gas, and an oxidizing step of supplying an oxidizing gas generated in the oxidizing gas generating step to a substrate surface heated to a predetermined temperature to oxidize an object to be processed. A method for manufacturing a semiconductor device, comprising:

The gist of the present invention is to provide a semiconductor device manufacturing apparatus for oxidizing an object to be processed exposed on a substrate surface with an oxidizing gas, by irradiating the gas to the object with the light being cut off. Oxidizing gas generating means for generating an oxidizing gas by oxidizing gas generated by the oxidizing gas generating means on a substrate surface heated to a predetermined temperature. Semiconductor device manufacturing apparatus.

[0011]

Embodiments of the present invention will be described below in detail with reference to the drawings. Prior to description of an embodiment of the present invention, a semiconductor device to which an embodiment of the present invention is applied will be described first.

Referring to FIG. 1 which is a schematic sectional view of a semiconductor device, a DRAM to which an embodiment of the present invention can be applied has the following structure.

An N well 4 is provided on the surface of the P-type silicon substrate 41.
2 are formed, and a first P well 43 is formed on the surface of the N well 2.
a is formed, and an N-type isolation region 45 is formed on the surface around the N well 42. A second P-well 43b is formed on the surface of the P-type silicon substrate 41 excluding the N-well.

The P-well 43a and the P-well 43b are separated from each other by the N-type isolation region 46 and a field oxide film 46 provided on the surface thereof.

On the surface of the first P well 43a, respective transistors 50 constituting memory cells are formed in active regions separated by a field oxide film 46. FIG. 1 shows only a pair of memory cells. Each transistor 50 includes N-type source / drain regions 51a, 5a provided on the surface of a P-well 43a.
1b, a gate insulating film 52 provided on the surface of the P-well 43a, and a polycrystalline silicon film 53 and a silicide film 54 provided on the surface of the P-well 43a via the gate insulating film 52. 55. These transistors 50 are covered with a first interlayer insulating film 47. The interlayer insulating film 47 is provided with a contact hole 58 reaching the (one) source / drain region 51a shared by the pair of transistors 50. Bit line 5 provided on surface of interlayer insulating film 47
Reference numeral 6 is connected to the source / drain region 51a via the contact hole 58.

The bit line 56 is connected to the second interlayer insulating film 48
Covered by On this interlayer insulating film 48,
A capacitive element portion 70 (enclosed by a dotted line) is provided. That is, the stack-type capacitive element according to the present embodiment includes the capacitive lower electrode 2A, the tantalum oxide film 11A as a capacitive insulating film, and the capacitive upper electrode 3A. A pair of transistors 50 penetrate through the interlayer insulating films 48 and 47.
(Other) N-type source / drain regions 5
A pair of capacitance lower electrodes 2A are connected to the respective source / drain regions 51b through the contact holes 57 that reach
It is connected to the. The upper electrode 3A is continuously formed in common with each of the capacitance elements of the pair of memory cells. The capacitor upper electrode 3A extends on the surface of the second interlayer insulating film 48, and is provided with a capacitor upper electrode 3Aa serving as an extraction portion for connecting to an upper layer wiring.

The capacitive element 70 is covered with a third interlayer insulating film 49. One of the plurality of aluminum electrodes 71 provided on the surface of the interlayer insulating film 49 is connected to the capacitor upper electrode 3Aa via a contact hole 67 provided in the interlayer insulating film 49. The aluminum electrode 71a has a fixed potential such as a ground potential. The side and bottom surfaces of the contact hole 67 are covered with a titanium nitride film 72, and the contact hole 67 is filled with a tungsten film 73. Also, the aluminum electrode 71
The titanium nitride film 72 is also provided on the bottom surface of the substrate.

On the other hand, the transistor 60 constituting the peripheral circuit of the storage device includes an N-type source / drain region 51 provided on the surface of the P well 43b, a gate insulating film 52 provided on the surface of the P well 43b, A gate electrode 55 is formed by laminating a polycrystalline silicon film 63 and a silicide film 54 provided on the surface of the P well 43b with the gate insulating film 52 interposed therebetween. Source / drain region 5
An aluminum electrode 71b is connected to one of the electrodes 1 through a contact hole 68 provided through the interlayer insulating films 47, 48, and 49. Like the contact hole 67, the side and bottom surfaces of the contact hole 68 are formed of the titanium nitride film 7.
2 and filled with a tungsten film 73. Similarly, the gate electrode 55 of another transistor 60 in the peripheral circuit is connected to the aluminum electrode 71c via a contact hole.

Next, a method of manufacturing a semiconductor device according to an embodiment of the present invention will be described. FIG. 2 is a cross-sectional view of the manufacturing process of the semiconductor device, and FIG. 2 is a partially enlarged cross-sectional view of the capacitive element section 70 of FIG. 1 and FIG. The form is as follows.

First, as shown in FIG. 2A, a second interlayer insulating film 48 is formed, and a contact hole 57 penetrating through the interlayer insulating films 47, 48 is formed. Thereafter, a polycrystalline silicon film doped with phosphorus is deposited by a chemical vapor deposition (CVD) method, and is patterned to form a capacitor lower electrode 2. The material for filling the inside of the contact hole 57 may be a metal material such as a tungsten film.

Next, as shown in FIG. 2B, after depositing, for example, polysilicon doped with phosphorus, W, etc., a stack electrode 2A is formed by, for example, RIE. further,
As shown in FIG. 2 (c), depositing a Ta2O5 capacitor insulating film 11A on the stack electrode 2A by LPCVD by example _{Ta (OC 2 H 5) 5} + O 2. The material for forming the capacitance insulating film 11A may be barium titanate or strontium titanate.

Next, an oxidation treatment method according to the present invention will be described with reference to FIG. In the figure, for example, oxygen is introduced from a gas inlet 21 and ozone is generated by an ozone generator 22. The gas introduced from the gas inlet 21 is O ₃ , N ₂
It may be O. The oxygen gas is converted into a mixed gas of ozone and oxygen by the ozone generator 22. This mixed gas is introduced into the oxygen radical generator 24. The oxygen radical generator 24 includes, for example, a low-pressure mercury lamp 23 therein.
Oxygen radicals are generated in the oxygen radical generator by the light emitted from the mercury lamp 23. Note that light from an excimer lamp may be applied instead of the mercury lamp.

The oxidizing gas containing oxygen radicals is introduced from the gas inlet 25 into the oxidizing tank 26, and a single-layer flow of the oxidizing gas flows over the surface of the substrate 29. The gas inlet 25 is preferably kept at 200 ° C. or lower. The processing chamber pressure is, for example, 500 Torr
r, oxidize the Ta2O5 film at a substrate temperature of, for example, 450 ° C. for 10 minutes. Oxygen radicals contained in the oxidizing gas diffuse in the Ta2O5 film and oxidize the Ta2O5 film. In this case, the substrate 29 is not irradiated with ultraviolet light, and no photoexcitation reaction occurs at the interface between the Ta2O5 film and the electrode. Most of the radicals are consumed in the Ta2O5 film. The oxidation of 2A) hardly proceeds.
Next, a second oxidation treatment is performed at 800 ° C. for 10 minutes in an oxygen atmosphere to oxidize and crystallize the Ta2O5 film.

Finally, for example, as shown in FIG.
The N capacitor upper electrode 3 is formed by, for example, sputtering so as to cover the capacitor insulating film 11A.

Therefore, according to the present embodiment, since the capacity insulating film 11A is oxidized by supplying oxygen radicals without irradiating the capacity insulating film 11A with ultraviolet light, a stack having a three-dimensional structure is provided. The uniformity of the film quality after the oxidizing process can be improved even with respect to the capacitive film formed on the electrode 2A, and the capacitive insulating film 11A can be selectively oxidized without significantly damaging the stack electrode 2A. can do. In addition, since the oxidizing gas is supplied to the oxidizing tank 26 as a single layer flow, the uniformity of the film quality can be further improved.

Further, the number, position, shape, etc. of the above-mentioned constituent members are not limited to the above-mentioned embodiment, but can be set to a suitable number, position, shape, etc. for carrying out the present invention. In the drawings, the same components are denoted by the same reference numerals.

[0027]

Next, the effects of the present invention will be clarified based on experimental results. From FIG. 4, it is found that the capacitance value at +1.5 V is 1.0 uF / cm ² in the capacitor formed with the electrodes by the oxidation treatment of the present invention. On the other hand, when oxidation is performed while irradiating the substrate with conventional ultraviolet light, the capacitance value at +1.5 V is 0.9 uF / cm ² . The capacitance of the capacitor formed according to the present invention is about 10% larger because the growth of the SiO ₂ film at the interface between Ta 2 O 5 and polysilicon is suppressed.

FIG. 5 is a distribution of capacitance values of capacitors on a 6-inch wafer. The variation of the capacitance value of the capacitor obtained by oxidizing the Ta2O5 film according to the present invention was smaller than that of the capacitor formed by the conventional technique.
As described above, according to the present invention, useful results can be obtained in the capacitor forming process.

[0029]

Since the present invention is configured as described above, the following effects can be obtained. That is, an efficient semiconductor manufacturing method capable of selectively acting on an object to be processed with low damage with good uniformity even with respect to an object to be processed such as a capacitor insulating film formed on a stack electrode having a three-dimensional structure. An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a semiconductor device to which an embodiment of the present invention is applied;

FIG. 2 is a process chart showing a method for manufacturing a semiconductor according to an embodiment of the present invention.

FIG. 3 is a schematic sectional view of an oxidation treatment apparatus to which an embodiment of the present invention is applied.

FIG. 4 is a diagram showing capacitance-voltage characteristics of capacitors manufactured according to the present invention and the prior art.

FIG. 5 is a diagram showing a capacitance distribution in a 6-inch wafer surface of a capacitor manufactured according to the present invention and the prior art.

[Explanation of symbols]

 2, 2A capacity lower electrode 3A, 3Aa capacity upper electrode 11A tantalum oxide film (capacitive insulating film) 21 gas inlet 22 ozone generator 23 mercury lamp 24 oxygen radical generating vessel 25 gas inlet 26 oxidation tank 27 cooling water pipe 28 heater 29 Substrate 30 Partition plate 31 Solenoid valve 32 Vacuum pump 41 P silicon substrate 42 N well 43 P well 43 a First P well 43 b Second P well 45 N type isolation region 46 Field oxide film 47 Interlayer insulating film 48 Second Interlayer insulating film 49 Third interlayer insulating film 50 Transistor 51 N-type source / drain region 51a Source / drain region 51b Source / drain region 52 Gate oxide film 53 Polycrystalline silicon film 54 Silicide layer 55 Gate electrode 56 Bit line 57 Contact hole 58 Contact hole 60 laps Transistor constituting side circuit 67 Contact hole 68 Contact hole 70 Capacitance element part 71, 71a, 71b, 71c Aluminum electrode 72 Titanium nitride film 73 Tungsten film

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Claims (10)

[Claims] 1. A method of manufacturing a semiconductor device, wherein an object to be processed exposed on a substrate surface is oxidized by an oxidizing gas, wherein the oxidizing gas is irradiated by irradiating a gas to the object in a state where light is blocked. An oxidizing gas generating step of generating the oxidizing gas; and an oxidizing step of supplying the oxidizing gas generated by the oxidizing gas generating step to the substrate surface heated to a predetermined temperature to oxidize the object to be processed. Manufacturing method of a semiconductor device. 2. The method according to claim 1, wherein the oxidizing gas generating step and the oxidizing step are performed in different chambers. 3. The method according to claim 1, wherein in the oxidizing gas generating step, light from a mercury lamp is irradiated. 4. The method according to claim 1, wherein in the oxidizing gas generating step, light from an excimer lamp is irradiated.
Or a method for manufacturing a semiconductor device according to item 2. 5. The method for manufacturing a semiconductor device according to claim 1, wherein in the oxidizing gas generating step, O ₂ , O _3, or N ₂ O is used as the gas. 6. The method for manufacturing a semiconductor device according to claim 1, wherein in the oxidizing step, the oxidizing gas is supplied as a single-layer flow onto the surface of the workpiece. 7. The method according to claim 1, wherein the object to be processed is a capacitive insulating film. 8. The method according to claim 7, wherein the object to be processed is one of tantalum oxide, barium titanate, and strontium titanate. 9. A semiconductor device manufacturing apparatus for oxidizing an object to be processed exposed on a substrate surface with an oxidizing gas, wherein the oxidizing gas is irradiated by irradiating gas to the object in a state where the object is blocked from light. An oxidizing gas generating unit that generates the oxidizing gas; and an oxidizing unit that supplies the oxidizing gas generated by the oxidizing gas generating unit to the substrate surface heated to a predetermined temperature to oxidize the workpiece. Semiconductor device manufacturing apparatus. 10. The apparatus for manufacturing a semiconductor device according to claim 9, wherein said oxidizing gas generating means and said oxidizing means form different chambers.