JP3252781B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to relates to a method of manufacturing a semiconductor device to oxidize the article to be treated on a substrate, e.g., Ta
_{The present} invention relates to a method for oxidizing a capacitive insulating film such as ₂ O ₅ .

[0002]

_2. Description of the Related Art A capacitor insulating film such as Ta ₂ O ₅ (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 Ta ₂ O ₅ film, defects in the film can be obtained by performing an oxidation treatment at 800 ° C. in an oxygen atmosphere, for example.
As the impurity density decreases, crystallization of Ta ₂ O ₅ occurs. As a result, a film with high stability is obtained, and defects and impurities are reduced, so that leakage current can be reduced. However, Ta ₂ O is used for highly integrated semiconductor memories.
_{When five} films are applied, 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 in 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 the electric field, so that T ions are accelerated.
Irradiate the a ₂ O ₅ 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 a complicated shape with irregularities due to the straightness 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.

In the case of UVO ₃ annealing in which an O ₃ gas is introduced into a processing vessel and ultraviolet light is applied to the processing chamber, the irradiation intensity of light caused by a light source in the substrate surface or the intensity of light caused by the structure of the substrate is increased. 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, since ultraviolet light is directly applied to the substrate, for example, when an SiO ₂ layer is present at the interface between the Ta ₂ O ₅ layer and the stack electrode, Ta ₂ O ₅
Is present at the interface because light reaches the lower layer of
Oxidation of the _two layers is also promoted, and there is a problem that the thickness of this layer increases and the defect density 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 method for manufacturing a semiconductor device, which has good uniformity, selectively acts on an object to be processed with low damage.

[0009]

Means for Solving the Problems] The gist of the invention described in claim 1 of the present invention, in a method of manufacturing a semiconductor device is oxidized by tantalum oxide film <br/> the oxidizing gas is exposed to the substrate surface, the substrate first the second interlayer insulating film (48) is formed on the interlayer insulating film (47), the first interlayer insulating film (4
7), the second interlayer insulating film (48) forming a contact hole (57) penetrating a capacitor lower and patterned by depositing a polycrystalline silicon film or tungsten film, which is phosphorus-doped by reduction Gakuki phase epitaxy Performing a first step of forming an electrode (2), followed by depositing phosphorus-doped polysilicon or tungsten and then forming a capacitive lower electrode (2A) by reactive ion etching; And then Ta (OC ₂ H ₅ ) ₅ + O ₂
On the capacitor lower electrode (2A) by LPCVD
In a third step of depositing an acid tantalum film (11A), followed by gas inlet (21) from the _O 2, _{O 3} or _{N 2} O and introduced ozone generator ozone by (22) The mixed gas is generated to generate a mixed gas, and the mixed gas is introduced into an oxygen radical generator (24) equipped with a low-pressure mercury lamp (23) or an excimer lamp to generate an oxygen radical.
An oxidizing gas containing oxygen radicals is generated, and then the oxidizing gas containing the oxygen radicals is supplied from the gas inlet (25) kept at 200 ° C. or lower through an oxidation treatment tank kept at 500 Torr.
Before being introduced into (26) and keeping the substrate temperature at 450 ° C.
Serial board (29) a single laminar flow of the oxidizing gas to the surface by flowing 10 minutes to oxidize the tantalum oxide film, and thereafter, performs a second oxidation treatment in an oxygen atmosphere 800 ° C. for 10 minutes, before
The tantalum oxide film is oxidized and crystallized, and thereafter, an oxidation treatment step of forming a TiN capacitor upper electrode (3) by sputtering so as to cover the tantalum oxide film (11A) is performed. A method for manufacturing a semiconductor device.

[0010]

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 the first P well 4 is formed on the surface of the N well 42.
3a are 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 first P well 43a and the second P well 4
The element 3b is isolated by the N-type isolation region 45 and a field oxide film 46 provided on the surface thereof.

On the surface of the first P-well 43a, respective transistors 50 forming 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 has a first P-well 4
N-type source / drain region 51 provided on surface 3a
a, 51b, a gate insulating film 52 provided on the surface of the first P well 43a , and the first
Gate electrode 5 formed by laminating a polycrystalline silicon film 53 and a silicide film 54 provided on the surface of the P well 43a of FIG.
And 5. These transistors 50
Are covered with a first interlayer insulating film 47. This second
The one 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. First interlayer insulating film
A bit line 56 provided on the surface of 47 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 the second interlayer insulating film 48, a capacitor element section 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. Each of the pair of transistors 50 (the other) penetrates the first interlayer insulating film 47 and the second interlayer insulating film 48.
The pair of capacitive lower electrodes 2A are connected to the respective source / drain regions 51b via the contact holes 57 reaching the N-type source / drain regions 51b. The upper electrode 3A is continuously formed in common with each of the capacitance elements of the pair of memory cells. This capacitor upper electrode 3A extends on the surface of the second interlayer insulating film 48,
A capacitor upper electrode 3Aa serving as a take-out portion for connection to an upper layer wiring is provided.

The capacitive element 70 is covered with a third interlayer insulating film 49. The third interlayer insulating film 4 is formed via a contact hole 67 provided in the third interlayer insulating film 49.
One of the plurality of aluminum electrodes 71 provided on the nine surfaces is connected to the capacitor upper electrode 3Aa. 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, a titanium nitride film 72 is provided on the bottom surface of the aluminum electrode 71 or the like.

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 second P well 43b and a second P well.
A gate insulating film 52 provided on the 43b surface, a gate electrode 55 second P-well 43b polycrystalline silicon film provided on a surface 63 and a silicide film 54 through the gate insulating film 52 is formed by stacking It is composed of The first interlayer insulating film 4 is formed on one of the source / drain regions 51.
7, an aluminum electrode 71b is connected through a contact hole 68 provided through the second interlayer insulating film 48 and the third interlayer insulating film 49 . Like the contact hole 67, the contact hole 68 is covered with a titanium nitride film 72 on the side and bottom surfaces, and is 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 7 through the contact hole.
1c.

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, the first layer
A second interlayer insulating film 48 is formed on between the insulating film 47, the
A contact hole 57 penetrating the first interlayer insulating film 47 and the second interlayer insulating film 48 is formed. Thereafter, chemical vapor deposition (C
A polycrystalline silicon film doped with phosphorus is deposited by VD) and 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, or the like, the capacitor lower electrode 2A is formed by, for example, RIE. further,
As shown in FIG. 2C, for example, Ta (OC ₂ H ₅ ) ₅ +
Oxidation on the lower capacitor electrode 2A by O ₂ by LPCVD
A tantalum film 11A (capacitive insulating film) is deposited. In addition, acid
Barium titanate or strontium titanate may be used as a material for forming the tantalum oxide film 11A (capacitive insulating film) .

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 O may be used. 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 into the oxidizing tank 26 through the gas inlet 25, 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 pressure of the processing chamber is set to, for example, 50
0 Torr, substrate temperature is set to, for example, 450 ° C. for 10 minutes
The Ta ₂ O ₅ film is oxidized. Oxygen radicals contained in the oxidizing gas is diffused _{the Ta} 2 _{O 5} film in oxidizing the the Ta ₂ O ₅ film. In this case, the substrate 29 is not irradiated with ultraviolet light and Ta ₂
O ₅ film and at the electrode interface by photoexcitation reaction does not occur, most of the radicals from being consumed by the Ta ₂ O ₅ film during T
For example, a polysilicon electrode below the a ₂ O ₅ film ( below the capacitor)
Oxidation of the electrode 2A ) hardly proceeds. Then perform a second oxidation treatment in an oxygen atmosphere 800 ° C. 10 minutes, Ta
_{The 2} O ₅ film is oxidized and crystallized.

Finally, for example, as shown in FIG.
The iN capacitor upper electrode 3A is connected to the tantalum oxide film 11A (capacitor).
It is formed by, for example, sputtering so as to cover the insulating film .

Therefore, according to this embodiment, the tantalum oxide
Oxygen radicals without irradiating ultraviolet light to the aluminum film 11A (capacitance insulating film) to form a tantalum oxide film 11A.
Since the (capacitive insulating film) is oxidized, the uniformity of the film quality after the oxidizing process can be improved even for the capacitive film formed on the capacitive lower electrode 2A having a three-dimensional structure, and
The tantalum oxide film 11A (capacitive insulating film) can be selectively oxidized without significantly damaging the capacitive lower electrode 2A . 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 suitable numbers, positions, shapes, etc. for carrying out the present invention. In the drawings, the same components are denoted by the same reference numerals.

[0026]

Next, the effect of the present invention will be described based on the experimental results.
Will be explained. Capacitor with electrodes formed by oxidation treatment of the present invention
In the case of Sita, the capacitance value at +1.5 V is 1.0 uF / cm
² . On the other hand, oxidation is performed while irradiating the substrate with conventional ultraviolet light.
The capacitance value at +1.5 V is 0.9 uF /
cm ² . Capacitors formed according to the present invention
Is the SiO ₂ film at the interface between Ta ₂ O ₅ and polysilicon
The capacitance value is about 10% larger because growth of GaN is suppressed.

According to the present invention, the Ta ₂ O ₅ film is oxidized.
Capacitor formed by conventional technology
The variation in the capacitance value was smaller than in the case of the above. This
As described above, according to the present invention, a capacitor useful in a capacitor forming process is provided.
Leads to fruit.

[0028]

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.

[Explanation of symbols]

2 , 2A capacity lower electrode 3A , 3Aa capacity upper electrode 11A tantalum oxide film (capacity insulating film) 21 gas inlet 22 ozone generator 23 mercury lamp 24 oxygen radical generator 25 gas inlet 26 oxidation treatment tank 27 cooling water pipe 28 heater 29 Substrate 30 Partition plate 31 Solenoid valve 32 Vacuum pump 41 P-type 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 First 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 Reference Signs List 60 Transistor constituting peripheral circuit 67 Contact hole 68 Contact hole 70 Capacitance element part 71 , 71a , 71b , 71c Aluminum electrode 72 Titanium nitride film 73 Tungsten film

Claims (1)

(57) [Claims] In a method of manufacturing a semiconductor device, wherein a tantalum oxide film exposed on a substrate surface is oxidized by an oxidizing gas, a second interlayer insulating film (48) is formed on a first interlayer insulating film (47) on a substrate. Is formed, and the first interlayer insulating film (4) is formed.
7), the second interlayer insulating film (48) forming a contact hole (57) penetrating a capacitor lower and patterned by depositing a polycrystalline silicon film or tungsten film, which is phosphorus-doped by reduction Gakuki phase epitaxy A first step of forming an electrode (2) is performed. Subsequently, after depositing polysilicon or tungsten doped with phosphorus, a second step of forming a capacitive lower electrode (2A) by reactive ion etching is performed. And then LPCVD with Ta (OC ₂ H ₅ ) ₅ + O ₂
On the capacitor lower electrode (2A) by law, a third step of depositing an acid tantalum film (11A), followed by, _O 2 from the gas inlet (21), _{O 3} or _{N 2}
O is introduced to generate ozone by an ozone generator (22) to generate a mixed gas, and the mixed gas is introduced to an oxygen radical generator (24) equipped with a low-pressure mercury lamp (23) or an excimer lamp. Oxygen radical
The oxidizing gas containing the oxygen radicals is generated at the gas inlet (2).
5) From the oxidation treatment tank (2 ) maintained at 500 Torr
Was introduced into 6), the single layer flow of the oxidizing gas to the base <br/> plate (29) surface which is holding the substrate temperature at 450 ° C. oxidizing the tantalum oxide film by flowing 10 minutes, thereafter, performing a second oxidation treatment of 800 ° C. 10 min in an oxygen atmosphere, the acid
The tantalum oxide film is oxidized and crystallized, and then
The capacitor upper electrode (3) of TiN is connected to the tantalum oxide film (1).
A method for manufacturing a semiconductor device, comprising performing an oxidation treatment step of forming a film by sputtering so as to cover 1A).