JP2979563B2 - Method for manufacturing semiconductor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention will be described in the following order.

A. Industrial application fields B. Summary of the invention C. Background art [Fig. 4] D. Problems to be solved by the invention [Figs. 5 and 6] E. Means for solving the problems F. Function G. Embodiment [FIGS. 1 to 3] a. First Embodiment [FIG. 1] b. Second Embodiment [FIG. 2] c. Third Embodiment [FIG. Figure] H. Effects of the Invention (A. Industrial Application Field) The present invention relates to a method of manufacturing a semiconductor device, and more particularly, to a trench formed in a surface portion of a substrate by bias ECRCVD using SiH ₄ / N ₂ O as a source gas. Embedded with the formed silicon oxide film,
Thereafter, by changing the flow rate ratio of the composition of the source gas, horizontal return etching is performed on the silicon oxide film outside the trench, and a space for forming a resist film serving as a mask when etching the silicon oxide film outside the trench is formed on the trench. The present invention relates to a method for manufacturing a secured semiconductor device.

(B. Summary of the Invention) The present invention relates to a method for manufacturing a semiconductor device as described above, wherein the flow rate ratio of source gas SiH ₄ to N ₂ O during horizontal return etching is adjusted to improve throughput. Is increased so that an etching promoting gas is added to the source gas.
× to 10 ^-4 ~1 × 10 ^-1 Torr, also in order to prevent the element forming region the surface of the substrate by the horizontal back etching is etched, likewise flat part etching rate for the flat portion during the horizontal back etching Is set to be smaller than the deposition rate.

(C. Background Art) [Fig. 4] Conventionally, isolation between elements of a semiconductor device such as IC, LSI, and VLSI is performed by a selective oxide film (LOCOS) formed by selectively oxidizing a surface portion of a semiconductor substrate. It was normal. However, the element isolation method using a selective oxide film has a disadvantage that a bird's beak is generated and a dimensional conversion difference is increased, so that it is becoming difficult to cope with miniaturization of the element. Therefore, attention has been paid to a trench isolation method in which bird's beaks are not generated and the difference in dimensional conversion is very small.

The trench isolation method is disclosed in, for example, JP-A-57-176742 or JP-A-60-53045.
A trench (groove) is formed in a surface portion of a semiconductor substrate, and the trench is filled with SiO ₂ by bias ECRCVD.

By the way, in the isolation method of filling a trench with a silicon oxide film, it is an important technique to remove the silicon oxide film grown on an active region outside the trench at the time of filling.

Therefore, a trench on the surface of the semiconductor substrate is buried with a silicon oxide film formed so that the surface is considerably thicker than the trench depth and the surface is flattened, and thereafter, a method of etching back, or a method in which the trench is approximately the same as or slightly less than the depth thereof A method of embedding a thick silicon oxide film, applying a resist film having substantially the same etching rate as that of the silicon oxide film, and then performing an etch-back method is considered.

However, these methods are troublesome because it is necessary to form a thick silicon oxide film or to form a resist film after forming the silicon oxide film and then remove the resist film by an etching apparatus.

Therefore, the inventor of the present application came up with the idea that by switching the conditions of the bias ECRCVD, it is possible to continuously perform the filling with the silicon oxide film and the removal of the silicon oxide film outside the trench. As a result of the search, embedding was performed by bias ECRCVD using SiH ₄ / N ₂ O as a source gas.
By changing the flow rate ratio between SiH ₄ and N ₂ O, a technique to perform horizontal return etching was developed.

According to this technique, source gases SiH ₄ / N ₂ O SiH ₄ in the N ₂ O
The silicon oxide film can be grown by changing the flow ratio of the silicon oxide film, or the silicon oxide film can be etched only in the horizontal direction without etching the flat surface, that is, the silicon oxide film can be etched back horizontally. Growing the film to fill the trench and then removing the silicon oxide film outside the trench by horizontal back-etching, which etches horizontally, can be done continuously with the same biased ECRCVD apparatus. Therefore, it can be said that the throughput can be improved.

Regarding this technique, a number of proposals have been made by developing it or variations thereof in Japanese Patent Application No. Hei 1-277930, etc., and the technique will be described here.

4 (A) to 4 (D) are sectional views showing the technique in the order of steps.

(A) After forming a trench 2 in the surface portion of a silicon semiconductor substrate 1, a silicon oxide film (Si) is formed by bias ECRCVD.
O ₂ ) 3 is formed and the trench 2 is filled with the silicon oxide film 3.

The conditions of the bias ECRCVD at the time of this embedding are, for example, the supply amount of SiH _{4 in} the supply gas is 17.5 SCCM, the supply amount of N ₂ O is 35 SCCM, and the power of microwave (2.45 GHz) is 100
0 W, RF bias (13.56 MHz) power 500 W, chamber pressure 7 × 10 ^-4 Torr, magnetic field 875 gauss. Under these conditions, the deposition rate exceeds the etching rate, and the silicon oxide film 3 grows. The silicon oxide film 3 is grown until its thickness becomes equal to the trench depth, that is, until the surface of the silicon oxide film 3 in the trench 2 becomes the same as the surface of the semiconductor substrate 1.

Incidentally, the silicon oxide film 3 also grows outside the trench, that is, on the active region, and 3a is a silicon oxide film grown on the active region. FIG. 4A shows a state after the silicon oxide film 3 is formed.

(B) Next, among the bias ECRCVD conditions, the supply amount of SiH ₄ is changed from 17.5 SCCM to 7 SCCM or less. Only the supply amount of SiH ₄ is changed, and other conditions do not need to be changed. Changing the supply of SiH _{4 is} of course
This is to change the flow ratio of SiH ₄ and N ₂ O in the supply gas SiH ₄ / N ₂ O. The flow ratio which was 1 to 2 when the silicon oxide film was embedded is reduced to about 1 (or less) in this step. : 5. Then, the deposition rate on the flat surface is equal to the etching rate, and the etching rate becomes larger than the deposition rate in the angled portion. As a result, the etching is performed as indicated by the arrow shown in FIG. Proceed only horizontally,
The width of the silicon oxide film 3a outside the trench gradually decreases. In the present specification, the horizontal return etching refers to such etching that narrows the width of the silicon oxide film 3a outside the trench, which proceeds in the horizontal direction. The first
FIG. 7B shows a state in the middle of the horizontal return etching, and the two-dot chain line shows the silicon oxide film 3a before the horizontal return etching.

(C) Next, as shown in FIG. 1C, a resist film 4 is selectively formed to mask the silicon oxide film 3 in the trench 2.

(D) Thereafter, the silicon oxide film 3a outside the trench 2 is etched, and then the resist film 4 is removed. Then
As shown in FIG. 4D, the inside of the trench 2 is filled with the silicon oxide film 3 and the silicon oxide film 3a outside the trench 2 is removed.

(D. Problems to be Solved by the Invention) [FIGS. 5 and 6] By the way, the above-mentioned technology developed by the present inventor also had a problem. One of the problems is that the time required for the horizontal return etching is long, so that it is difficult to sufficiently increase the throughput. This is because the difference between the etching rate on the inclined side surface of the silicon oxide film 3a outside the trench 2 and the deposition rate at the time of the first horizontal return etching cannot be sufficiently large. I have.

This will be specifically described below with reference to FIG. FIG. 5 shows a plane angle θ at the time of horizontal return etching in the method of manufacturing the semiconductor device shown in FIG.
FIG. 5 is an angle-rate relationship diagram showing the relationship between the etching rate and the deposition rate. Where the surface angle θ
Is the angle of the surface with respect to the horizontal plane, and the horizontal plane (flat surface) is 0
Degrees, and the vertical plane is 90 degrees.

As is clear from this figure, while the deposition rate is constant irrespective of the angle θ, the etching rate has a dependency on the angle θ. When the angle θ is 0 degree, the etching rate is And the deposition rate are equal, and the etching rate is higher than the deposition rate for a plane with an angle, so that the horizontal return etching can be performed.However, the factors that contribute to the horizontal return etching are the etching rate and the etching rate at that angle. ,
This is the difference from the deposition rate. The difference cannot be made sufficiently large according to the above-mentioned technology.

In addition, the fact that the throughput could not be sufficiently increased also results from the fact that an appropriate value of the gas pressure in the chamber could not be grasped until now.

That is, the inventor's earnest research has revealed that the etching rate (and the deposition rate) depends on the gas pressure in the chamber, and that the rate of horizontal return etching should be increased without considering the gas pressure. It turned out to be impossible.

Next, a second problem of the above technique will be described. That is, there is a problem that the surface portion of the element formation region of the semiconductor substrate may be etched by the horizontal return etching.
As described above, the horizontal return etching is performed such that the etching rate and the deposition rate are equal on a horizontal plane (flat surface) and the etching rate is higher than the deposition rate at an angled portion. The etching rate with respect to the horizontal plane often became larger than the deposition rate due to subtle deviations and the like. It is especially the source gas monosilane Si
It was easy to occur by the flow variation of H _4. This is because the flow rate of SiH ₄ and the etching / deposition rate have a relationship shown in FIG. 6, and the supply rate of SiH _{4 is set} so that the total rate of etching and deposition on the horizontal plane (flat surface) becomes zero. The horizontal return etching is selectively performed (a in FIG. 6 is a point where the total rate becomes 0).
Supply amount of H ₄ is naturally overall rate and uneven resulting in biased to either the deposition side and etching side. If it is shifted to the etching side, the surface of the semiconductor substrate 1 will be etched at the time of horizontal return etching. Since the surface portion of the semiconductor substrate 1 is a region where elements are formed except for the trench 2, it is not preferable that the surface portion is etched.

The present invention has been made to solve these problems, and a trench formed on the surface of the substrate is buried with a silicon oxide film formed by bias ECRCVD using SiH ₄ / N ₂ O as a source gas. After that, the flow rate ratio of the composition of the source gas is changed to perform horizontal back etching on the silicon oxide film outside the trench, and a space for forming a resist film serving as a mask when etching the silicon oxide film outside the trench above the trench. It is an object of the present invention to provide a method of manufacturing a semiconductor device which ensures an improvement in throughput and in which the surface of an element formation region of a substrate can be prevented from being etched by horizontal return etching.

(E. Means for Solving the Problems) In the first method of manufacturing a semiconductor device of the present invention, the flow rate ratio of the source gas SiH ₄ to N ₂ O at the time of horizontal back etching is determined by adjusting the etching and deposition rates. It is characterized in that the etching gas is increased to be larger and an etching promoting gas is added to the source gas.

A second method of manufacturing a semiconductor device according to the present invention is that the gas pressure during horizontal return etching is set to 1 × 10 ^-4 to 1 × 10 ^-1 To.
rr. Among them, 3 × 10 ^{−3 to} 9 × 10 ⁻² Torr is particularly preferable.

A third method of manufacturing a semiconductor device according to the present invention is characterized in that the etching rate for the flat portion during the horizontal return etching is set to be smaller than the deposition rate for the flat portion.

(F. Action) According to the first method of manufacturing a semiconductor device of the present invention,
During the horizontal return etching, the flow rate ratio of SiH ₄ to N ₂ O of the source gas is made higher than before, so that the etching and deposition rates can be increased as shown in FIG. Accordingly, the difference between the etching rate and the deposition rate increases accordingly, and as a result, the rate of horizontal return etching increases.

In addition, since the etching promoting gas is added to the source gas, only the etching rate can be further increased. Therefore, the rate of horizontal return etching can be further increased.

Accordingly, the rate of the horizontal return etching can be effectively increased, and the throughput can be improved.

According to the second method of manufacturing a semiconductor device of the present invention,
Gas pressure during horizontal return etching is 10 ^-4 to 10 ^-1 Torr
Therefore, as shown in FIG. 2, the etching rate can be made relatively high, so that the throughput can be improved. In addition, since the supply amount of SiH ₄ is more than up to now by a slight variation in the SiH ₄ etching, deposition rate is not affected most. Therefore, it is possible to eliminate the possibility that the etching rate exceeds the deposition rate and the surface portion of the substrate is etched by the horizontal return etching.

Note that the gas pressure is particularly 3 × 10 ^-3 in 10 ^-4 to 10 ^-1 Torr.
By setting the pressure to 9 × 10 ^-2 Torr, the etching rate can be further increased as shown in FIG.

According to a third method of manufacturing a semiconductor device of the present invention,
Since the etching rate is made smaller than the deposition rate during the horizontal return etching, the surface portion of the substrate can be completely prevented from being etched by the horizontal return etching. In this case, a silicon oxide film remains on the surface of the substrate after the horizontal return etching, but this is not a problem since it can be easily removed by, for example, etching back.

(G. Embodiment) [FIGS. 1 to 3] Hereinafter, a method for manufacturing a semiconductor device of the present invention will be described in detail with reference to illustrated embodiments.

(A. First Embodiment) [FIG. 1] FIG. 1 is an angle / rate relation diagram for explaining a first embodiment of a method of manufacturing a semiconductor device of the present invention.

This embodiment is different from the method for manufacturing the semiconductor device shown in FIGS. 4A to 4D in the bias ECRCVD conditions of the horizontal return etching step [see FIG. 4B].
The other points are common, and the common points have already been described, so only the different points will be described in the present embodiment.

In the method of manufacturing the present semiconductor device, the rate of etching and deposition is increased as shown in FIG. 1 by increasing the flow rate ratio of SiH ₄ in the source gas SiH ₄ / N ₂ O during horizontal return etching as compared with the conventional case. Increase.

That is, the supply amount of the source gas SiH ₄ at the time of the horizontal back etching was 7 SCCM and the supply amount of N ₂ O was 35 SCCM in the past, but in the manufacturing method of the semiconductor device, the source gas SiH ₄ at the time of the horizontal back etching is used. Is increased to, for example, 35 SCCM, and the supply amount of N ₂ O is kept at 35 SCCM. In short, SiH
_It increases the flow ratio of ₄ to N ₂ O. Then
As shown in FIG. 1, both the etching rate and the deposition rate increase. By the way, since the etching rate and the deposition rate increase at substantially the same rate, the ratio between the etching rate and the deposition rate does not change from the previous case, but the etching rate for the originally angled surface is higher than the deposition rate. It's getting bigger
There was a difference between the etching rate and the deposition rate. Therefore, if the etching rate and the deposition rate increase at the same rate, the difference (etching rate-deposition rate) also increases at the same rate.
Accordingly, the substantial rate (etching rate-deposition rate) of the horizontal return etching is increased, so that the time required for the horizontal return etching can be reduced, and the throughput can be improved.

As described above, the throughput can be remarkably improved only by increasing the flow rate ratio of SiH ₄ to N ₂ O. However, in the method of manufacturing the semiconductor device, the etching rate is further increased by adding an etching promoting gas to the source gas. High.

Specifically, for example, argon Ar is used for about ₂₀ to 40 SCCM N ₂ O
In the same manner as above, it is added from the upper side of the plasma generation chamber. When argon (Ar) is added, this acts only as an etchant, and the etching rate alone can be further increased without increasing the deposition rate at all. Therefore, the rate of the horizontal return etching can be further increased, and the rate of the horizontal return etching can be actually increased to about five times the conventional rate.

As an etchant, Kr, Ne, and He, which are the same rare gases, can be used in addition to argon Ar. Instead of a rare gas, a halogen-based material that does not emit a deposition component such as NF ₃ (supply amount, for example, 20 to 50 SCCM) is used. Can also be used. As such a halogen-based etching gas, NF is used.
₃ In addition, for example _{HCl, HBr, Br 2, F} 2, Cl 2, ClF 3, SF 6,
CF ₄ , C ₂ F ₆ , NF _{3 and the} like can be used.

It should be noted that although a rare gas such as argon Ar which does not cause a chemical reaction is most preferable as the etching promoting gas, the above-mentioned etching gas which does not emit a halogen-based deposition component can be sufficiently used.

(B. Second Embodiment) [FIG. 2] FIG. 2 is a pressure-rate relationship diagram for explaining a second embodiment of the method of manufacturing a semiconductor device of the present invention.

In the present embodiment, the bias EC during the horizontal return etching is also used.
There is a feature only in the RCVD condition, and only the feature will be described.

The inventor of the present application could not recognize the importance of the relationship between the pressure during the horizontal return etching and the etching rate (and the deposition rate) at first, but due to slight variations in the flow rate of SiH ₄ , In the face of the problem of the surface being etched, he came to recognize its importance.

Because, as described above, SiH as shown in FIG. 6 ₄
A slight change in the flow rate changes the difference between the etching rate and the deposition rate, and the etching rate may be higher than the deposition rate. Therefore, focusing on the point that increasing the total gas pressure may be effective in order that the difference between the etching rate and the deposition rate does not fluctuate so much even if the flow rate of SiH ₄ slightly varies. It was done. That is, increasing the total gas pressure is to increase the flow rate of the inevitably SiH _4, by increasing the flow rate of SiH ₄ Si
Difference change of the etching rate and the deposition rate even if there is some variation in the supply amount of H ₄ by which is to be reduced.

Thus, as a result of an experiment, it was found that there was a relationship between the total gas pressure and the etching rate (and the deposition rate) as shown in FIG. This figure shows the angle θ
Is a pressure / rate change diagram for a plane of about 50 degrees.

As a result, in order to perform the horizontal return etching so that the etching rate does not become too low, the pressure in the chamber during the horizontal return etching is set to 10 ⁻⁴ to 10 ⁻¹ To
It can be said that rr is preferable.

However, it is more preferable that the pressure is 3 × 10 ^{−3 to} 9 × 10 ⁻² Torr. This is because the etching rate can be further increased.

Incidentally, an experimental example when the gas pressure in the chamber is set to 3 × 10 ⁻³ Torr will be described. In this example, the supply amount of SiH ₄ is 20 SC
The supply amounts of CM and N ₂ O were set to 100 SCCM. Therefore, the supply amount of SiH ₄ is equal to that in the case of the semiconductor device manufacturing method shown in FIG.
M), which is about three times as large, and even if there is the same variation in the supply amount of SiH ₄ , the influence exerted by the difference between the etching rate and the deposition rate is only about one-third, so the etching rate is reduced. The possibility that the surface portion of the substrate 1 is etched by the horizontal return etching, which greatly exceeds the rate, is extremely reduced.

Increasing the gas pressure in this way corresponds to decreasing the slope of the line indicating the flow rate / rate relationship shown in FIG.

Since both the etching rate and the deposition rate increase as a whole, the rate of the horizontal return etching, that is, the retreat speed by the horizontal return etching of the angled surface increases, and the throughput improves.

Note that, in this embodiment, the SiH ₄
The flow rate ratio to N ₂ O may be increased so that the etching rate and the deposition rate become larger.
NF ₃ may be added. That is, this embodiment and the first
Can be used in combination.

(C. Third Embodiment) [FIG. 3] FIGS. 3A and 3B are cross-sectional views showing a third embodiment of the method of manufacturing a semiconductor device of the present invention in the order of steps.

(A) As shown in FIG. 4 (A), the horizontal return etching performed after the trench 2 is buried with the silicon oxide film 3 is performed at the same etching rate with respect to the horizontal plane (flat plane) than the deposition rate with respect to the horizontal plane. Is performed under small conditions. In this case, although the horizontal return etching is completed, a thin silicon oxide film 3 remains on the surface of the substrate as shown in FIG.
It may be removed later, for example, by etch back.

The reason why the etching rate is made smaller than the deposition rate is to prevent the surface of the substrate 1 from being etched by horizontal return etching. That is, as in the case of the technique shown in FIG. 4, the horizontal return etching is performed, and the supply amount of SiH ₄ is 7.5 SCCM and the supply amount of N ₂ O is 35 SCC.
Under the conditions of M, gas pressure of 7 × 10 ^-4 Torr, μ wave power of 1 KW, and RF bias power of 0.5 KW, both the deposition rate and the etching rate should be 400 ° / min. Also vary by about ± 10%. Therefore, for example, if the etching rate is shifted by + 10% to 440 ° / min and the deposition rate is shifted by -10% to 360 ° / min, the surface of the substrate 1 is etched at a rate of 80 ° / min. . It is rare to make such an extreme variation, but a case close to it is frequent. Therefore, the bias ECRCVD conditions at the time of the horizontal return etching are set so that the etching rate is lower than the deposition rate so that such a case cannot occur.

As one example of setting such conditions, the supply amount of SiH ₄ is set to 7S.
Raising from CCM to 12SCCM. The supply amount of N ₂ O is the same.

In this case, the deposition rate is 490
Å / min, the etching rate becomes 400 Å / min, and the deposition rate shifts by -10%. Even if the etching rate shifts by + 10%, the etching rate does not exceed the deposition rate and the substrate 1 surface is etched by horizontal return etching. There is no danger.

(B) Next, as shown in FIG. 3B, the thin silicon oxide film 3 on the surface of the substrate 1 generated during the horizontal back etching by etching back is removed.

Thereafter, the silicon oxide film 3 in the trench 2 is masked with the resist film 4 in the same manner as in the method of manufacturing the semiconductor device shown in FIG. 4 [see FIG.
The outer silicon oxide film 3 is removed, and the resist film 4 is also removed [see FIG. 4 (D)].

In the present embodiment, in order to increase both the etching rate and the deposition rate during the horizontal return etching, the flow rate ratio of SiH ₄ to N ₂ O is increased, and an etching promoting gas is added to the source gas. The gas pressure may be increased to increase the throughput. That is, this embodiment can use the first and second embodiments together.

(H. Effects of the Invention) As described above, the first method of manufacturing the semiconductor device of the present invention is that the source gas Si
The flow rate ratio of H ₄ to N ₂ O is increased so that the etching and deposition rates are both increased, and an etching promoting gas is attached to the source gas.

Therefore, according to the first method of manufacturing the semiconductor device of the present invention, the N _{2 of the} source gas SiH ₄ is used during the horizontal return etching.
Since the flow rate ratio to O is made higher than before to increase the etching and deposition rates, the difference between the etching rate and the deposition rate increases accordingly. Therefore, the rate of horizontal return etching increases. In addition, since the etching promoting gas is added to the source gas, only the etching rate can be further increased. Therefore, the rate of horizontal return etching can be further increased.

Accordingly, the rate of the horizontal return etching can be effectively increased, and the throughput can be improved.

A second method of manufacturing a semiconductor device according to the present invention is that the gas pressure during horizontal return etching is set to 1 × 10 ^-4 to 1 × 10 ^-1 To.
rr.

Therefore, according to the second method of manufacturing a semiconductor device of the present invention, as shown in FIG. 2, the etching rate can be relatively increased, and the throughput can be improved. Moreover, depending on slight variation of SiH ₄ by increasing the supply amount of SiH ₄ than the conventional etching,
The rate of deposition can be hardly affected. Accordingly, it is possible to eliminate the possibility that the etching rate exceeds the deposition rate and the surface portion of the substrate is etched by the horizontal return etching.

A third method of manufacturing a semiconductor device according to the present invention is characterized in that the etching rate for a flat portion during the horizontal return etching is set lower than the deposition rate for the flat portion.

Therefore, according to the third method of manufacturing the semiconductor device of the present invention, the etching rate for the flat portion is set lower than the deposition rate for the flat portion during the horizontal return etching, so that the surface portion of the substrate is etched by the horizontal return etching. Can be completely prevented. In this case, a silicon oxide film remains on the surface of the substrate after the horizontal return etching, and can be easily removed by, for example, etch back.

[Brief description of the drawings]

FIG. 1 is an angle-rate relationship diagram for explaining a first embodiment of the method for manufacturing a semiconductor device of the present invention, and FIG. 2 is a diagram for explaining a second embodiment of the method for manufacturing a semiconductor device of the present invention. FIGS. 3 (A) and 3 (B) are sectional views showing a third embodiment of the method of manufacturing a semiconductor device of the present invention in the order of steps, and FIGS. 4 (A) to 4 (D) are background arts. 5 is an angle-rate relationship diagram for explaining a problem to be solved by the invention, and FIG. 6 is a SiH for explaining another problem to be solved by the invention. _{4 is a} flow rate / rate relationship diagram. DESCRIPTION OF SYMBOLS 1 ... substrate, 2 ... trench, 3 ... silicon oxide film, 4 ... mask.

Claims (3)

(57) [Claims] A trench formed in a surface portion of a substrate is made of SiH _4.
Buried with a silicon oxide film formed by bias ECRCVD using / N ₂ O as a source gas, and thereafter, the silicon oxide film outside the trench is horizontally returned etched by changing the flow rate ratio of the composition of the source gas. A method for manufacturing a semiconductor device, in which a space for forming a resist film serving as a mask during etching of a silicon oxide film outside a trench is secured, wherein a flow ratio of source gas SiH ₄ to N ₂ O is etched during the horizontal return etching. A method of manufacturing a semiconductor device, wherein the deposition rate is increased so as to increase, and an etching promoting gas is added to the source gas. 2. A trench formed in a surface portion of a substrate is formed of SiH _4.
ECRC with at least / N ₂ O as the main source gas
Filled with silicon oxide film formed by VD, then
With respect to the flow rate ratio of SiH ₄ to N ₂ O of the source gas, the etching rate and the deposition rate are equal for a flat surface, and the etching rate is larger than the deposition rate for an angled portion. A method for manufacturing a semiconductor device in which the silicon oxide film outside the trench is horizontally back-etched by changing the thickness as described above to secure a space for forming a resist film serving as a mask when etching the silicon oxide film outside the trench on the trench. The gas pressure during the horizontal return etching is 1 × 10 ⁻⁴ to
A method for manufacturing a semiconductor device, wherein the pressure is 1 × 10 ^-1 Torr. 3. A trench formed in a surface portion of a substrate is formed with SiH _4.
ECRC with at least / N ₂ O as the main source gas
Filled with silicon oxide film formed by VD, then
The silicon oxide film outside the trench is horizontally back-etched by changing the flow ratio of the composition of the source gas to secure a space for forming a resist film serving as a mask when etching the silicon oxide film outside the trench on the trench. A method of manufacturing a semiconductor device, wherein an etching rate for a flat portion during the horizontal return etching is set lower than a deposition rate for the flat portion.