JPH0338038A - Formation of insulating film - Google Patents

Abstract

PURPOSE:To form a silicon oxide insulating film in step-difference, and excellently flatten the surface by a method wherein vapor growth of the insulating film is performed by using silane based N2O as reaction gas, and controlling microwave output. CONSTITUTION:When an insulating film is formed on a substrate 11 provided with step-difference 10 by bias ECR plasma CVD method, silane based N2O is especially used as the reaction gas, and the CVD of a silicon oxide insulating film 12 is performed by controlling the microwave output. Hence the over hang of the insulating film 12 is not generated on the substrate 10 provided with step difference like a trench. Thereby the insulating film 12 can be densely formed in the manner in which the surface is flat and cavities are not generated in the trench, and the insulating film 12 of high reliability can be obtained.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention is directed to forming an element isolation insulating film or a glabella insulating film in a semiconductor integrated circuit, etc. on a substrate having a step using a bias, electron, cyclotron, resonance plasma, etc. Vapor phase growth method (hereinafter referred to as bias ECR plasma CVD)
It relates to a method of forming an insulating film by a method (referred to as a method).

[Summary of the invention]

The present invention relates to (1) a method for forming an insulating film, in which silane/N2O is used as a reactive gas when forming an insulating film on a substrate having steps by bias ECR plasma CVD method;
CVD of the insulating film is performed by controlling the microwave output, or CVD of the insulating film is performed by controlling the flow rate ratio of the silane gas of the reaction gas and N, O on a substrate having a step. To form a high-quality insulating film having a flat surface by filling the inside of the step well without causing overhang.

[Conventional technology]

The bias ECR plasma CVD method is used to meet the demand for higher integration in semiconductor integrated circuits, and is used to form an insulating film with a flat surface, such as an insulating film between the eyebrows, or to form a step in, for example, a wiring conductive layer formed thereon. It is attracting attention as a technology that has the potential to meet demands such as the prevention of micropatterns and the high-precision formation of fine patterns.

Since this bias ECR plasma CVD method can form high-density plasma at low pressure, it is possible to grow an insulating film at high speed even in a trench with a large aspect ratio, that is, a trench with a large depth relative to the trench width. In addition, in this case, by applying an RF (radio frequency) bias to the CVD substrate, for example, a semiconductor wafer, an etching effect and an insulating film deposition effect occur simultaneously, and the combination of these causes an overhang that covers the trench opening. This method has the advantage that it is possible to form a flat insulating film within the trench and on the wafer surface above it without causing any formation.

Moreover, it has the advantage that low-temperature growth of an insulating film is possible by using low-temperature plasma.

Furthermore, by taking advantage of the characteristics of the bias ECR plasma CVD method, it is possible to apply the bias ECR plasma CVD method to, for example, insulation isolation of the isolation region between semiconductor elements in a semiconductor integrated circuit device.
Research and development on embedding SiO□ insulating films and the like using CR plasma CVD is actively being conducted. Usually, this Si0
The formation of the g insulating film is performed using a Sitlmlot reaction gas system. However, in the case of using this reactive gas system, as shown in FIG. 9, for example, when a Si0g film (3) is formed in a trench (2) formed in a Si semiconductor wafer (1), the trench (2) is formed in the process. ) An overhang (4) is generated that covers the opening of the hole. Furthermore, when forming the insulating film without applying RF bias to the semiconductor wafer (1), the S
The iO□ film (3) becomes rough. Therefore, when forming this type of insulating film, the overhang can be reduced by increasing the etching rate (etching rate refers to (etching rate/depositing rate)) by applying a high RF bias. However, applying such a high RF bias to the wafer causes the problem of wafer heating, and even if cooling means are provided, the wafer cannot be cooled sufficiently. ing. Furthermore, in this case, if Ar is applied in the initial process, the Si wafer and the oxide film on the inner wall of the trench will be etched, so Ar cannot be added in the initial process. Therefore, in this case, by increasing the microwave power, the etching component (the etchant in this case is thought to be 02°, etc.) is increased, and the Si0g insulating film is deposited while obtaining the effect of removing this overhang. I'm going to go there. However, in this case, the reaction gas is 5il141
In the case of the 0x system, when the microwave power is increased, the etching rate (input/min) increases, as shown for example by curve (32) in FIG. 9, but at the same time, the deposition rate (input/min) increases. minute) also rises significantly as shown by curve (31) in the figure, making it difficult to suppress this overhang. This becomes more noticeable as the aspect ratio increases, such as when filling a 5iO1 film into a deep trench for isolation between elements.

[Problem to be solved by the invention]

The present invention is directed to the formation of silicon oxide (SiOx, 5
The main purpose of this method is to form an insulating film (iOxNy) and planarize its surface well to form a highly reliable insulating film.

[Means to solve the problem]

In the present invention, for example, when an insulating film is formed on a substrate (11) having a step (10) by bias ECR plasma CVD as shown in the cross-sectional view in FIG. This C
In the VD method, by controlling the microwave output or (and) controlling the flow rate ratio of the silane system to the reactant gas N2O, silicon oxide (SiOx) is deposited as shown in the cross-sectional view of FIG. 1B.

5iOxNy) CVD of the insulating film (12) is performed.

Incidentally, as the silane gas here, 5ixl (yXz
For example, Sin, Si, H,, 5i)1. F, 5
iH3Ci'l 5tuzpz.

5iHzlJz etc. can be used, and Ar can also be mixed with N2O in the silane type/N2O.

[Effect]

When using the above-mentioned method of the present invention, the level difference (l) of the trench etc.
Forming the insulating film (12) densely on the substrate (1) having O) without overhanging the insulating film (12) so that the surface is flat and without creating a cavity in the trench. I was able to do that.

That is, in the present invention, the control of microwave output,
or (and) a reactive gas, especially silane/Nz.

By controlling the gas flow rate, deposition and etching can occur simultaneously in a well-balanced manner, and the flattening is achieved by the action of both.

〔Example〕

Figure 2 is a schematic diagram of an example of a bias ECR plasma CVD apparatus, where (21) is a reaction chamber;
), the base body (11) is arranged. (22) is a support that supports this base (11), and (23) is a high frequency oscillator that applies an RF bias to this. Also,(
24) is a silane-based gas inlet for the reaction gas, and (25) is an exhaust port. (26) is the plasma generation chamber, (27)
is the microwave introducing section, (28) is the magnetic field generating coil, (2
9) shows a plasma gas inlet in which Ar is mixed with Neo or N2O.

Example 1 Using the apparatus explained in FIG.
4) respectively from 35 SCCM and 5iHa of N2O.
was introduced with 21 SCCM and pressure cuff x 10-
' Torr, the RF power is 500 W, and the microwave is varied in the range of 200 to 100 OW, and an insulating film ( 12) was produced. In this case, the deposition rate and etching rate when the microwave power was changed were as shown by curves (41) and (42) in FIG. 3, respectively.

As is clear from comparing FIG. 3 with FIG. 9, in the case of the embodiment of the present invention, that is, when a 5iHn/NzO-based reaction gas is used, compared to the case of FIG. 9 where a 5iH410x-based reaction gas is used. However, when increasing the microwave power, it is possible to increase the rate of change of the etching rate with respect to the deposition rate, that is, the etching rate Rr. FIG. 4 shows the dependence of this etching rate RF on microwave power. The curve (43) in FIG. 4 is different from the curve (43) in the case of FIG. 44) is the case shown in Fig. 9, that is, the case using a 5iHa10x-based reaction gas, and it is found that by using a SiH4/N2O-based reaction gas, the dependence of the microwave power can be strengthened compared to the case where a 5iH410□-based gas is used. Recognize.

Note that the etching speed here refers to the RF speed to the substrate (11).
When the bias is set to OW (state B where no deposition occurs), the etching rate is set to R1°, and the RF bias is set to 5.
It is R1°-RD when the deposition speed is R11 when the power is 00W.

Example 2 The inlet (29) and (
24) respectively from 35 SCCM and 5iH of N2O.
n is 17.5SCCM, that is, the flow rate ratio of SiHm and N2O F <5=Ha, 7F <wzo> =0. ．． 5
and a pressure cuff Xl0-'Torr, a microwave power of 1.000 W, an RF power of 500 W, and a base made of a silicon semiconductor having a step (lO) (11).
An insulating film (12) was formed thereon. In this case, the insulating film (12) could be formed without overhanging. In this Example 2, the deposition rate and etching rate were measured while changing the flow rate ratio F<s=wa>7F (N2O) of SiH4 and NZO.

Curves (51) and (52) in FIG.
(tiH4) / F (82) Figure 6 shows the measurement results of the deposition rate and etching rate when changing O1. According to this, F (Si
The etching rate can be controlled by changing the amount of H41/F (H□., ie, 5t)I<.

In the above example, monosilane Si is used as the silane gas.
This is the case using H4, but in addition, 5iJi+SiH
3F, 5iHaα, 5fHth+5tthα, etc. can be used. Furthermore, it is also possible to use N2O in addition to Ar.

Further, in the above embodiment, the etching rate is controlled by controlling the microwave power or by controlling F (siH1/F (810)), but it is also possible to control both at the same time.

〔Effect of the invention〕

As described above, according to the present invention, in bias ECR plasma CVD, microwave power or/and S
The etching rate can be controlled by controlling the flow rate of iN4, and by controlling the etching rate, it is possible to form a step (lO), especially a groove with a large aspect ratio, such as a trench groove for element isolation, without causing an overhang. The insulating film (12) can be favorably formed on the substrate (11) having the structure so as to fill the inside of the trench.

In other words, if we look at the relationship between the deposition rate and the etching rate with respect to the incident angle of deposition (the angle θ with the normal to the surface on which the insulating film is formed) of the deposition in Figure 7, these are shown by the broken line curve (71) in Figure 7. and solid curve fi1 (72), a point occurs where both coincide at predetermined incident angles α and β, and the deposition rate becomes dominant in the range of θ from 0 to α and β, and α -β, the etching rate becomes dominant.

Therefore, as shown in Figure 8, ts and t□t are sequentially deposited on the base (11) having the step (10) from the lower layer.

....t, the step difference (10
) As shown in the stacked state between the lower part of the step (10) and the upper part of the step (10), when the slope becomes equal to or greater than α due to the progress of the deposit, the deposition on this slope almost stops, resulting in a flat surface of the deposit. A film, namely an insulating film (12), is produced.

Therefore, in the present invention, as described above, the microwave output or (and) F (-114>/F (.).

. By controlling the angles α and β in FIG. 7, a flat insulating film (12) can be formed while avoiding large steps and neck overhangs.

As described above, according to the present invention, it is possible to form an insulating film that is flat as a whole including the inside of a trench, so that it can be applied to the manufacture of semiconductor integrated circuits, etc., to improve reliability, reduce the occupied area, and therefore increase the Integration can be achieved.

[Brief explanation of drawings]

Fig. 1 is a process diagram of an example of the method of the present invention, Fig. 2 is a schematic diagram of an example of a bias ECR plasma CVD apparatus implementing the method of the present invention, and Fig. 3 is a graph showing the relationship between the deposition rate and the etching rate with respect to microwave power. Figure 4 shows the measurement results of the dependence of etching rate on microwave power. Figure 5 shows the relationship between 5iHn and N2.
Figure 6 shows the measurement results of the relationship between the O flow rate ratio and the deposition rate and etching rate.
FIG. 7 is a diagram showing the dependence of etching rate and deposit rate on the incident angle. FIG. 8 is a cross-sectional view showing the formation mode of SiO□ film. Figure 9 is a diagram showing the measurement results of etching and deposition speed of 5iH410x type insulating film, Figure 10.
The figure shows SiO□ film growth t1. J! ! FIG. (lO) is a step, (11) is a base, and (12) is an insulating film. Agent Hidemori Matsukuma'@4 Figure Hori'nR Seijo n Haruru 1 Meeting 4 Figure Y Figure Prefecture 9 Figure

Claims (1)

[Claims] 1. In an insulating film method in which an insulating film is formed on a substrate having steps by bias electron cyclotron resonance plasma vapor phase epitaxy, using silane/N_2O as a reactive gas, An insulating film forming method characterized by performing vapor phase growth of an insulating film by controlling wave output. 2. In an insulating film forming method in which an insulating film is formed on a substrate having steps by bias electron cyclotron resonance plasma vapor phase epitaxy, silane/N_2O is used as a reactive gas, and the silane-based gas as the reactive gas is An insulating film forming method characterized by performing vapor phase growth of an insulating film by controlling the flow rate ratio of and N_2O gas.