JP3396791B2 - Method of forming insulating film - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for forming an insulating film, and more particularly to a method for forming an interlayer insulating film using organic silicon having a silazane bond used in a semiconductor integrated circuit device.

[0002]

2. Description of the Related Art Conventionally, in a semiconductor integrated circuit device,
A multilayer wiring structure has been adopted, and an ordinary interlayer insulating film such as a CVD film formed of monosilane has been used to insulate each wiring layer. However, as the number of wiring layers increases as the degree of integration increases, and the increase in steps due to this increase easily causes poor coverage of the wiring layers, it is essential to flatten the steps caused by the wiring layers. Was there.

As a conventional flattening technique, TEOS (T
Etra-Ethyl-Ortho-Silicat
e) a method of reacting ozone (O ₃ ) to form a silicon oxide film, or applying SOG (spin-on-glass) to heat treatment, and then etching back to remove the SOG film from the lower wiring layer, A method such as newly forming an insulating film on the entire surface by using the CVD method has been adopted.

[0004]

However, as shown in FIG. 2, TEOS-NSG film (TEOS-Nondoped-Si11cate-G) is produced by reacting TEOS with ozone.
The method of forming the (lass) is performed in a region where the distance between the wiring layers 3 made of aluminum alloy or the like formed on the base insulating layer 2 such as the BPSG film is wide, that is, in the wide step portion, the step portion is a silicon oxide film. However, there was a drawback in that the surface was not flattened sufficiently.

Further, the method using SOG requires a combination of a plurality of processes such as coating, heat treatment, etchback, and deposition of a CVD film, resulting in a long turnaround time (TAT: required processing time) and a manufacturing process. This method has the disadvantage of increased cost. Furthermore, the method using SOG requires two types of equipment, a spin coater and a CVD equipment, and these two types of equipment are not compatible with each other, so that one equipment is used. The drawback was that they could not be put together.

Therefore, the present invention provides a method for manufacturing an insulating film, which is capable of flattening the entire surface including a wide step portion by a simple film forming process and further capable of depositing an insulating film having good film quality. It is intended.

[0007]

The present invention is directed to plasma chemistry.
Using the vapor deposition method (plasma CVD method), silazane
Among the organic silicon having a bond, -C is used as a side chain group._n
H_{2n + 1}Have (n = 0, 1, 2, 3, ... N)(S
iR ₂ NR ') ₃ [However, R and R'are -C _n H
_{2n + 1} Side chains represented by (n = 0, 1, 2, 3, ... N)
Group] or (SiR ₂ NR ') _Four [However, R and R'are
-C _n H _{2n + 1} (N = 0, 1, 2, 3, ... n), Some
Is -OC as a side chain group._nH_{2n + 1}(N = 1, 2, 3, ...
..Mixed gas of n) or H and oxidizer
Is characterized in that an insulating film is deposited by plasma reaction of
To do.

[0008]

[Function] When forming an insulating film by the plasma CVD method
And -C as a side chain group_nH_{2n + 1}(N = 0, 1, 2, 3,
... n)(SiR ₂ NR ') ₃ [However, R and
And R'is -C _n H _{2n + 1} (N = 0, 1, 2, 3, ...
n) side chain group] or (SiR ₂ NR ')
_Four [However, R and R'are -C _n H _{2n + 1} (N = 0, 1,
2, 3, ... n), Or —OC as the side chain group_nH
_{2n + 1}(N = 1,2,3, ... n) or a series having H
Deposition when using organosilicon having a lazan bond
Since the insulation film has extremely high fluidity in the stage,
Even if there is a step, it is possible to flatten the entire semiconductor device.
It will be possible.

As a side chain group, --OC _n H _{2n + 1} (n =
1,2,3, ... n) or H containing silazane bond-containing organic silicon, the resulting insulating film contains almost no organic component, so that the quality of the insulating film is improved. To do.

[0010]

EXAMPLES Hereinafter, a method of forming an insulating film according to two examples of the present invention will be described with reference to FIG. In addition, in FIG.
A base insulating layer 2 such as a BPSG film on a silicon semiconductor substrate 1.
Is formed, a conductive film of an aluminum alloy or the like is deposited thereon by sputtering to a thickness of 1 μm, and the wiring layer 3 is formed by patterning, and then the plasma CV according to the present invention is formed.
This shows a state in which the D film 4 is formed, and the structure is common to the two examples.

First Embodiment A silicon semiconductor substrate 1 on which a wiring layer 3 of aluminum alloy or the like is formed as described above is introduced into a parallel plate type plasma CVD apparatus and is represented by the general formula (SiR ₂ NR ′) ₃ . As a side chain group (R and R ′), —C _n H _{2n + 1} (n = 0, 1,
Hexamethylcyclotrisilazane (Si ₃ C ₆ H ₂₁ N ₃ , abbreviated as HMCTS, which is one of the organic silicon having 2, 3, ... N) and has the structure shown in FIG.
Z: Si is used to form an insulating film by using a mixed gas of R ₃ which is n = 1 and CH ₃ where R is n and R ′ which is bonded to N is n = 0) and oxygen as an oxidant. is there.

[0012]

[Chemical 1]

In this case, the silicon semiconductor substrate 1 has about 10
H heated to a temperature of 0 ° C and bubbled with helium gas
A mixed gas of MCTSZ and oxygen is introduced into the plasma CVD apparatus so that the flow ratio of oxygen to helium, which is a carrier gas of HMCTSZ, is 1: 2. Since the source HMCTSZ is bubbled at a constant temperature, the supply amount of HMCTSZ is uniquely determined by the flow rate of He.

Then, high frequency power having a frequency of 13.56 MHz is applied to the parallel plate electrodes of the plasma CVD apparatus so that the power density becomes 0.4 W / cm ^2, and HMCTSZ is applied.
A mixed gas of oxygen and oxygen is turned into plasma, and an insulating film 4 is deposited to a thickness of 0.7 μm so as to cover the wiring layer 3 on the silicon semiconductor substrate 1. As a result, as shown in FIG.
Insulating film 4 obtained even in a wide step portion with a wide interval
Surface is flattened.

In this case, since the insulating film 4 has extremely high fluidity in the deposition step, the insulating film portion on the wiring layer 3 flows out to the step portion when 0.5 μm is deposited, and the entire step portion having a height of 1 μm is flown. After embedding, the entire structure becomes substantially flat. After that, when further 0.2 μm (total 0.7 μm) is deposited, the entire surface including the wiring layer 3 having a height of 1 μm is covered with the insulating film 4 and planarized.

Although hexamethylcyclotrisilazane (Si ₃ C ₆ H ₂₁ N ₃ ) is used in the first embodiment, it is not limited to hexamethylcyclotrisilazane, and hexamethylcyclotrisilazane is used. It has a structure represented by the following structural schematic diagram 2 containing silazane, is represented by the general formula (SiR ₂ NR ′) ₃ , and has —C _n H as a side chain group.
_{Organosilicon} having a silazane bond having _{2n + 1} (n = 0, 1, 2, 3, ... N) may be used.

[0017]

[Chemical 2]

Further, R bound to octamethylcyclotetrasilazane (Si ₄ C ₈ H ₂₈ N ₄ : Si is CH
_3, having the structure shown in structural Scheme 3 below in which R 'is H) are known for binding to N, the general formula (SiR ₂ N
R ′) ₄ is represented by —C _n H _{2n + 1} (n =
Organosilicon having a silazane bond having 0, 1, 2, 3, ... N) may be used.

[0019]

[Chemical 3]

In the first embodiment, oxygen is used as the oxidant, but nitric oxide (NO) or dinitrogen monoxide (N ₂ O) may be used instead of oxygen. The effect is obtained, and even when the organic silicon having the structure of the above structural schematic diagram 2 or 3 other than hexamethylcyclotrisilazane (Si ₃ C ₆ H ₂₁ N ₃ ) is used as the organic silicon, an oxidizing agent is also used. Alternatively, nitric oxide (NO) or nitrous oxide (N ₂ O) may be used.

[0021] Next, -OC as side groups _n H _2n + 1 _(n =
A second embodiment using organic silicon having a silazane bond having 1, 2, 3, ... N) or H will be described. This embodiment improves the film quality of the insulating film obtained in comparison with the first embodiment, but the plasma CVD apparatus used in this second embodiment and the silicon semiconductor for depositing the insulating film are used. The structure of the substrate is the same as that of the first embodiment.

Second Example Represented by the general formula (SiR ₂ NR ′) ₃ and having a side chain group of —
_{OC n H 2n + 1 (n} = 1,2,3, ··· n) is one of the organic silicon with or H, hexamethoxymethylmelamine cyclotrimethylene silazane (Si having the structure shown in schematic structure 4
₃ C ₆ H ₂₁ N ₃ O ₆ : R is n = 1 OCH ₃ and R ′ is H (abbreviation is also HMCTSZ) and an insulating film is formed using a mixed gas of oxygen as an oxidant To do.

[0023]

[Chemical 4]

In this case, the silicon semiconductor substrate 1 is approximately 1
HMCTSZ and oxygen which have been heated to a temperature of 00 ° C. and bubbled with helium gas are introduced into the plasma CVD apparatus so that the flow rate ratio of oxygen to helium, which is the carrier gas of HMCTSZ, is 1:10. The insulating film 4 is deposited.

From the infrared absorption spectrum analysis, since the plasma CVD insulating film formed according to the second embodiment has no absorption peak corresponding to the organic component, the plasma CVD insulating film formed according to the first embodiment is obtained. Compared with the film, the residual organic component in the film is extremely small, and the film quality is improved because it is closer to a pure oxide film. Further, the obtained flatness is similar to that of the first embodiment.

In this case, the flow rate ratio between oxygen and helium which is the carrier gas of HMCTSZ is 1:10,
Good results are obtained up to 1:20, but conversely 1: 5
Then, the obtained shape becomes worse. That is, better results are obtained when the oxygen content is lower, but good results are not obtained when the oxygen content is too low.

In the second embodiment, although the substrate temperature is 100 ° C., a good result can be obtained even at 50 ° C., but a good result cannot be obtained at 150 ° C. or higher. That is, since the process of the present invention is an extremely low temperature process, re-diffusion of impurities in the already formed impurity region does not occur, which is a preferable process for a highly integrated semiconductor device.

In the second embodiment, hexamethoxycyclotrisilazane (Si ₃ C) is used as the organic silicon.
Although using _{6 H 21 N 3 O 6)} , it is not limited to hexa methoxy cyclotrimethylene silazane having the structure shown in schematic structure 5 below that contains hexamethoxymethylmelamine cyclotrimethylene silazane of the general formula (SiR ₂ NR ′) ₃ and as a side chain group, —OC _n H _{2n + 1} (n = 1, 2, 3, ...
..N) or H-containing organosilicon having a silazane bond may be used.

[0029]

[Chemical 5]

As another organic silicon, hexamethoxydisilazane (Si ₂ C ₆ H ₁₉ NO ₆ : R is OC
In H _3, structural schematic below which R 'is H) are known for Figure 6
Represented by the general formula (SiR ₃ ) ₂ NR ′ having a structure shown in, and as a side chain group, —OC _n H _{2n + 1} (n = 1, 2,
3, ... N) or H-containing organosilicon having a silazane bond may be used.

[0031]

[Chemical 6]

Further, octamethoxycyclotetrasilazane (Si ₄ C ₈ H ₂₈ N ₄ O ₈ : R is OCH ₃ and R '
Is represented by the general formula (SiR ₂ NR ′) ₄ , which has a structure shown in the following structural schematic diagram 7 known as H) or the like and has —OC _n H _{2n + 1} (n = 1, 2, 3, ... N) or H-containing organosilicon having a silazane bond may be used.

[0033]

[Chemical 7]

In the second embodiment, oxygen is used as the oxidant, but nitric oxide (NO) or dinitrogen monoxide (N ₂ O) may be used instead of oxygen. Hexamethoxycyclotrisilazane (Si ₃ C ₆ H ₂₁ N ₃ O ₆ ) as organic silicon
Besides, in the case of using the organic silicon having the structures of the above structural schematic diagrams 5 to 7, nitric oxide (N
O) or dinitrogen monoxide (N ₂ O) may be used.

[0035] In the case of using an organic silicon represented by the general formula described above, in order to reduce the formed organic groups in absolute Enmaku was may be used as a lot of hydrogen as possible as side groups However, since organic silicon containing a large amount of hydrogen becomes an active compound and becomes dangerous to handle, it is necessary to appropriately determine the side chain group in consideration of the balance thereof.

Furthermore, in the above embodiments, the silicon semiconductor substrate having a wiring layer forming the insulating film, the present invention is limited to a silicon semiconductor substrate, not even of a, the other compound semiconductor substrate Also applies.

[0037]

According to the present invention, the surface of a semiconductor substrate having a wide step portion is formed by a low temperature process by using a simple plasma CVD method using an organic silicon having a silazane bond as a silicon source of an insulating film. Therefore, it is possible to flatten the surface, and thus to prevent the coverage failure of the multi-layered wiring layer, which greatly contributes to high integration or high speed of the semiconductor integrated circuit device.

[Brief description of drawings]

FIG. 1 is a diagram showing a deposition state of an insulating film formed by a plasma CVD method according to an embodiment of the present invention.

FIG. 2 T formed by a conventional reaction between TEOS and O _3.
It is a figure which shows the deposition condition of an EOS-NSG film (silicon oxide film).

[Explanation of symbols]

1 Silicon Semiconductor Substrate 2 Base Insulating Layer 3 Wiring Layer 4 Insulating Film 5 Formed by Plasma CVD Method TEOS-N Formed by Reaction of TEOS and O ₃
SG film

Claims (7)

(57) [Claims] 1. A using a plasma chemical vapor deposition, having a silazane bond (SiR ₂ NR ') ₃ [Here, R及
And R ′ are −C _n H _{2n + 1} (n = 0, 1, 2, 3, ...
n)), and a mixed gas of an oxidizing agent and a plasma reaction to deposit an insulating film. 2. A plasma chemical vapor deposition method is used to
(SiR ₂ NR ′) ₄ having a lazan bond [provided that R and R
And R ′ are −C _n H _{2n + 1} (n = 0, 1, 2, 3, ...
n) and the gas mixture of oxidizer and plasma reaction to insulate
A method for forming an insulating film, which comprises depositing a film. 3. A plasma chemical vapor deposition method is used to
As a chain group, —OC _n H _{2n + 1} (n = 1, 2, 3, ...
n) or organic silico having a silazane bond having H
Insulation film by plasma reaction of mixed gas of oxygen and oxidant
A method for forming an insulating film, which comprises depositing 4. The organic silicon having a silazane bond is (SiR ₃ ) ₂ NR ′ [wherein R and R ′ are −
4. The method for forming an insulating film according to claim 3, wherein a side chain group represented by OC _n H _{2n + 1} (n = 1, 2, 3, ... N) or H] is used. 5. The organic silicon having a silazane bond is (SiR ₂ NR ′) ₃ [wherein R and R ′ are −
4. The method for forming an insulating film according to claim 3, wherein a side chain group represented by OC _n H _{2n + 1} (n = 1, 2, 3, ... N) or H] is used. 6. The organic silicon having a silazane bond is (SiR ₂ NR ′) ₄ [wherein R and R ′ are −
4. The method for forming an insulating film according to claim 3, wherein a side chain group represented by OC _n H _{2n + 1} (n = 1, 2, 3, ... N) or H] is used. 7. The oxidizing agent is oxygen, nitric oxide,
And method of forming a dielectric film according to any one of claims 1 to 6, characterized by using any one of dinitrogen monoxide.