JP6267374B2 - Silicon film deposition method - Google Patents

Description

  The present invention relates to a method for forming a silicon film.

  Silicon, for example, amorphous silicon, is used as a thin film for embedding contact holes and lines of semiconductor integrated circuit devices and forming elements and structures. A method for forming an amorphous silicon film is described in, for example, Patent Documents 1 and 2. Patent Document 1 describes a method of thermally decomposing monosilane at 400 to 600 ° C. to form an amorphous silicon film, and Patent Document 2 decomposes at 400 to 500 ° C. for disilane and 350 to 300 for trisilane. A method is described in which an amorphous silicon film is formed by decomposing at 450 ° C. and decomposing at 300 to 400 ° C. for tetrasilane.

  However, if an attempt is made to fill a contact hole or line that has been miniaturized with amorphous silicon, the amorphous silicon after film formation has poor coverage at the contact hole portion, and a large void is generated. When a large void occurs in a contact hole or line, for example, it becomes one of the factors that cause an increase in resistance value. This is because the accuracy of the surface roughness of the amorphous silicon film is poor.

  Therefore, in order to improve the accuracy of the surface roughness of the amorphous silicon film, an aminosilane-based gas is supplied on the base surface before forming the amorphous silicon film, and a seed layer is formed in advance on the base surface. Patent Documents 3 and 4 describe a method for forming an amorphous silicon film.

JP-A 63-29954 Japanese Unexamined Patent Publication No. 1-221756 JP 2011-249664 A JP 2013-95945 A

  In recent years, however, the demand for further thinning of the silicon film, for example, an amorphous silicon film, has become increasingly severe, along with the demand for improving the surface roughness accuracy.

  In Patent Documents 3 and 4, the purpose of improving the accuracy of surface roughness can be achieved. However, in consideration of the demand for further thinning, pinholes are likely to occur in the vicinity of the order of 2 nm, and the thickness is reduced to the order of 2 nm or less. There is a situation that becomes difficult.

  Further, in Patent Document 4, there is a description that, in addition to the aminosilane-based gas, the silicon layer in the molecular formula can be used for forming the seed layer, for example, hexakisethylaminodisilane can be used. There is no description about specific examples using hexakisethylaminodisilane.

  The present invention has been made in view of the above circumstances, and is capable of responding to the demand for further thinning, and can improve the accuracy of surface roughness. Alternatively, a technique for forming a silicon film on an object to be processed having a groove is provided.

A silicon film forming method according to the present invention is a silicon film forming method for forming a silicon film on an object to be processed having holes or grooves on the surface to be processed. A step of supplying a high-order aminosilane-based gas containing two or more silicons in the molecular formula to adsorb silicon on the surface to be treated to form a first seed layer; and (2) the first seed layer. A step of supplying a higher order silane-based gas containing two or more silicons in the molecular formula and not containing amino groups, and depositing silicon on the first seed layer to form a second seed layer; 3) supplying a silane-based gas not containing an amino group on the second seed layer and depositing silicon on the second seed layer; and (4) etching the silicon film. And the silicon film is formed on the bottom of the hole or groove. Comprising a to step, wherein the (1) from said step (4) repeats the process, the said holes or grooves in the surface to be processed, embedded by the silicon film which is repeatedly formed, the process in the step (1) The temperature is set to 350 ° C. or lower and room temperature (25 ° C.) or higher.

  According to the present invention, it is possible to cope with the demand for further thinning, and to improve the accuracy of the surface roughness, on the target object having holes or grooves on the target surface. A silicon film forming method for forming a silicon film can be provided.

1 is a flowchart showing an example of a sequence of a silicon film forming method according to the first embodiment of the present invention; (A) Drawing-(C) figure is a sectional view showing roughly the state of a processed object in the sequence shown in Drawing 1. Diagram showing the relationship between processing time and film thickness Diagram showing the relationship between processing temperature and film thickness A diagram showing the relationship shown in FIG. 4 as an Arrhenius plot The figure which shows the relationship between the process temperature of the seed layer 3, and the film thickness of the silicon film 4 formed on the seed layer 3 The figure which shows the relationship between the process pressure of the seed layer 3, and the film thickness of the silicon film 4 formed on the seed layer 3 The figure which shows the relationship between the process pressure of the seed layer 3, and the haze of the surface of the silicon film 4 formed on the seed layer 3. (A) is a sectional view showing a case where the adsorption density of silicon is high, and (B) is a sectional view showing a case where the adsorption density of silicon is low. The figure which shows the relationship between the processing time of the seed layer 3, and the film thickness of the silicon film 4 formed on the seed layer 3 The figure which shows the relationship between the processing time of the seed layer 3, and the haze of the surface of the silicon film 4 formed on the seed layer 3 Drawing substitute photograph showing secondary electron image of surface of silicon film 4 when source gas is monosilane Drawing substitute photograph showing secondary electron image of surface of silicon film 4 when source gas is higher order silane The flowchart which shows an example of the sequence which concerns on the application example 1 of the film-forming method of the silicon film which concerns on the 2nd Embodiment of this invention (A) The figure-(D) figure is sectional drawing which shows the state of the to-be-processed object in the sequence shown in FIG. 14 roughly FIGS. 5A to 5F are cross-sectional views schematically showing the state of an object to be processed in an example of a sequence according to an application example 2 of the silicon film forming method according to the second embodiment of the invention. Sectional drawing which shows the state which has diffused the impurity with respect to the seed layer 3 and the 2nd seed layer 3a Sectional drawing which shows the state which has diffused the impurity with respect to the silicon film 4 after an etching FIGS. 4A to 4C are cross-sectional views for explaining the definition of “etching coverage”. (A) is a cross-sectional view showing an initial state of the hole or groove 5, (B) is a cross-sectional view showing a case where the aspect ratio of the opening 6 is “37.5”, and (C) is a view showing the opening 6 Sectional drawing which shows the case where the aspect ratio of "12" is Diagram showing the relationship between aspect ratio and etching coverage FIGS. 4A to 4I are cross-sectional views schematically showing a state of an object to be processed in an example of a sequence according to an application example 3 of the silicon film forming method according to the second embodiment of the invention. Sectional drawing which shows the state which has diffused the impurity with respect to the seed layer 3 and the 2nd seed layer 3a Sectional drawing which shows the state which has diffused the impurity with respect to the silicon film 4 after an etching FIGS. 4A to 4D are cross-sectional views schematically showing the state of the object to be processed in another example of the sequence according to the application example 3 of the silicon film forming method according to the second embodiment of the invention. (A) and (B) are sectional views showing an example of doping into the second seed layer. (A) and (B) are sectional views showing examples of doping into a silicon film. Sectional drawing which shows the other dope example to a 2nd seed layer Sectional drawing which shows the other example of dope to a silicon film (A) to (C) are sectional views showing the final shape of the silicon film. Sectional drawing which shows roughly an example of the film-forming apparatus which concerns on 3rd Embodiment of this invention The figure which shows the modification of a process gas supply mechanism

  Embodiments of the present invention will be described below with reference to the drawings. Note that common parts are denoted by common reference numerals throughout the drawings.

(First embodiment)
<Definitions in the specification>
In this specification, when it is described as amorphous silicon, it is not a term indicating only amorphous silicon, but nanocrystalline silicon in which amorphous to nano-sized crystal grains that can achieve the accuracy of surface roughness disclosed in this specification are collected, and the above It is defined as a term including all of silicon in which amorphous silicon and the nanocrystalline silicon are mixed.
In this specification, 1 Torr is defined as 133 Pa.

<Film formation method>
FIG. 1 is a flowchart showing an example of a sequence of a silicon film forming method according to the first embodiment of the present invention, and FIGS. 2A to 2C are objects to be processed in the sequence shown in FIG. It is sectional drawing which shows the state of.

  First, the target object illustrated in FIG. 2A, for example, the silicon substrate 1 is carried into the processing chamber of the film formation apparatus. A silicon oxide film 2 is formed on the silicon substrate 1. In this example, the surface of the silicon oxide film 2 is a surface to be processed on which a silicon film is formed. The silicon oxide film 2 may be any of a natural oxide film, a thermal oxide film, and a CVD film.

  Further, the surface to be processed is not limited to the silicon oxide film 2. For example, the silicon substrate 1 itself may be a surface to be processed, or a substance containing silicon, for example, a silicon film, a silicon nitride film, a silicon oxynitride film, a silicon carbide film, or a silicon oxycarbonitride film may be used. Further, it may be a low dielectric constant insulating film or a metal film.

  Next, as shown in FIGS. 1 and 2B, silicon is adsorbed on the surface (surface to be processed) of the silicon oxide film 2 to form the seed layer 3. The seed layer 3 is supplied with a high-order aminosilane-based gas (hereinafter abbreviated as a high-order aminosilane-based gas) containing two or more silicons in the molecular formula on the surface of the silicon oxide film 2 as a processing gas. It is formed. The processing temperature for forming the seed layer 3 is 350 ° C. or lower and room temperature (25 ° C.) or higher (step 1).

Examples of higher order aminosilane gases include
_{((R1R2) N) n Si} X H 2X + 2-n-m (R3) m ... (A), or _{((R1R2) N) n Si} X H 2X-n-m (R3) m ... (B)
However, in the formulas (A) and (B),
n is the number of amino groups and is a natural number of 1 to 6 m is the number of alkyl groups and is a natural number of 0 and 1 to 5 R1, R2, R3 = CH ₃ , C ₂ H ₅ , C ₃ H ₇
R1 = R2 = R3, or may not be the same R3 = Cl may be sufficient. X is an amino compound of silicon represented by a natural number of 2 or more. A gas containing at least one kind of silicon amino compound represented by the above formula (A) and the above formula (B) can be selected as the processing gas used in step 1.

As an example of the higher order aminosilane-based gas represented by the above formula (A),
Diisopropylaminodisilane (Si ₂ H ₅ N (iPr) ₂ )
Diisopropylaminotrisilane (Si ₃ H ₇ N (iPr) ₂ )
Diisopropylaminochlorodisilane (Si ₂ H ₄ ClN (iPr) ₂ )
Diisopropylaminochlorotrisilane (Si ₃ H ₆ ClN (iPr) ₂ )
Etc. As the processing gas, at least one of these gases can be selected.

In addition, as an example of the higher-order aminosilane-based gas represented by the above formula (B),
Diisopropylaminocyclotrisilane (Si ₃ H ₅ N (iPr) ₂ )
Diisopropylaminochlorocyclotrisilane (Si ₃ H ₄ ClN (iPr) ₂ )
Etc. As the processing gas, at least one of these gases can be selected.

  In this example, diisopropylaminodisilane (hereinafter referred to as DIPADS) represented by the above formula (A) was used.

An example of the processing conditions in Step 1 is
DIPADS flow rate: 200sccm
Processing time: 1 min
Processing temperature: 250 ℃
Processing pressure: 133 Pa (1 Torr)
It is.

  Next, as shown in FIGS. 1 and 2C, silicon is deposited on the seed layer 3 to form a silicon film 4 (step 2). The silicon film 4 is formed by supplying a silane-based gas containing no amino group on the surface of the seed layer 3 as a processing gas. The formed silicon film 4 is, for example, amorphous silicon.

Examples of silane gases that do not contain amino groups include:
Si _X H _{2X + 2} (where X is a natural number of 1 or more) (C) or Si _X H _2X (where X is a natural number of 1 or more) (D)
A silicon hydride represented by the formula: A gas containing at least one kind of silicon hydride represented by the above formula (C) and the above formula (D) can be selected as a processing gas (silicon source gas) in step 2.

As an example of the hydride of silicon represented by the above formula (C),
Monosilane (SiH ₄ )
Disilane (Si ₂ H ₆ )
Trisilane (Si ₃ H ₈ )
Tetrasilane (Si ₄ H ₁₀ )
Pentasilane (Si ₅ H ₁₂ )
Hexasilane (Si ₆ H ₁₄ )
Heptasilane (Si ₇ H ₁₆ )
Can be mentioned. The processing gas used in Step 2 can be selected from at least one of these gases.

Moreover, as an example of the hydride of silicon represented by the above formula (D),
Cyclotrisilane (Si ₃ H ₆ )
Cyclotetrasilane (Si ₄ H ₈ )
Cyclopentasilane (Si ₅ H ₁₀ )
Cyclohexasilane (Si ₆ H ₁₂ )
Cycloheptasilane (Si ₇ H ₁₄ )
Can be mentioned. The processing gas used in Step 2 can be selected from at least one of these gases.

In this example, monosilane (SiH ₄ ) represented by the above formula (C) was used.

An example of the processing conditions in Step 2 is
SiH ₄ flow rate: 500 sccm
Deposition time: 10min
Deposition temperature: 510 ℃
Stacking pressure: 53.2 Pa (0.4 Torr)
It is.

  As described above, according to the method for forming a silicon film according to the first embodiment, a high-order aminosilane-based gas is supplied onto the surface (surface to be processed) of the silicon oxide film 2, and the silicon oxide film 2 is formed. After the seed layer 3 is formed by adsorbing silicon on the surface (step 1), a silane-based gas not containing an amino group is supplied onto the seed layer 3, and silicon is deposited on the seed layer 3 to form the silicon film 4 Is formed (step 2).

  Furthermore, according to the method for forming a silicon film according to the first embodiment, the processing temperature in step 1 is set to 350 ° C. or lower and room temperature (25 ° C.) or higher. The advantages of this will be described below.

<Relationship between treatment temperature and reaction mode>
First, the relationship between the processing temperature and the reaction mode of the silicon film formed by the higher order aminosilane-based gas will be described.

FIG. 3 is a diagram showing the relationship between processing time and film thickness. The vertical axis in FIG. 3 indicates the film thickness of the silicon film formed by the high-order aminosilane-based gas, and the horizontal axis indicates the processing time. The relationship shown in FIG. 3 is obtained under the following processing conditions.
Processing gas: DIPADS
Process gas flow rate: 200sccm
Processing temperature: 300 ° C, 350 ° C, 375 ° C, 400 ° C
Processing time: 1 min or 10 min
Processing pressure: 133 Pa (1 Torr)

  As shown in FIG. 3, when the processing time is increased from 1 min to 10 min, the thickness of the formed silicon film increases. However, it has been found that the growth rate tends to become extremely large between the case where the treatment temperature is 350 ° C. and the case where the treatment temperature is 375 ° C., despite a difference of only 25 ° C. This is because if the processing temperature is 350 ° C. or lower, the reaction mode is not a deposition reaction (CVD reaction) but an adsorption reaction, and if the processing temperature exceeds 350 ° C., the reaction mode is not changed from an adsorption reaction to a deposition reaction. I guess it is not. Therefore, the inventors of the present application reduced the flow rate of DIPADS and advanced a finer analysis on the change of the reaction mode.

FIG. 4 is a diagram showing the relationship between the processing temperature and the film thickness. The relationship shown in FIG. 4 is obtained under the following processing conditions.
Processing gas: DIPADS
Process gas flow rate: 50sccm
Processing temperature: 200 ° C, 250 ° C, 300 ° C, 350 ° C
375 ° C, 400 ° C, 425 ° C, 450 ° C
Processing time: 10 min
Processing pressure: 133 Pa (1 Torr)

  As shown in FIG. 4, even when the flow rate of DIPADS is lowered to 50 sccm, the silicon film has a thickness of between 350 ° C. and 375 ° C., similarly to the case where the DIPADS flow rate is 200 sccm. It was found that the film thickness tends to increase.

FIG. 5 is a diagram showing the relationship shown in FIG. 4 as an Arrhenius plot.
As shown in FIG. 5, in the region where the processing temperature is 350 ° C. or lower, the Arrhenius plot shows almost no inclination. That is, DIPADS is not activated. Further, when the processing temperature exceeds 350 ° C., a slope appears in the Arrhenius plot. That is, DIPADS is activated.

  From the relationship shown in FIG. 5, it is confirmed that the DIPADS reaction mode is an adsorption reaction in a region where the processing temperature is 350 ° C. or lower, and the DIPADS reaction mode is a deposition reaction in a region where the processing temperature exceeds 350 ° C. It was. The present application is an invention effective for forming the seed layer 3. The seed layer 3 is not required to have a thick film thickness. For this reason, the seed layer 3 may be formed by adsorbing silicon on the surface to be processed. Therefore, the processing temperature is preferably 350 ° C. or lower and room temperature (25 ° C.) or higher from the viewpoint that the seed layer 3 is formed by a silicon adsorption reaction using a high-order aminosilane-based gas.

  As described above, when the seed layer 3 is formed using the high-order aminosilane-based gas, the processing temperature is set to 350 ° C. or lower and room temperature (25 ° C.) or higher, so that the formed seed layer 3 is treated with silicon. The seed layer 3 can be formed by being adsorbed thereon, and the advantage that the thickness of the seed layer 3 can be reduced can be obtained.

<Seed effect in the region where the processing temperature is 350 ° C. or lower>
Next, the seed effect in the region where the processing temperature is 350 ° C. or lower will be described.

[1. Relationship between processing temperature of seed layer 3 and film thickness of silicon film 4]
After setting the processing conditions as follows, the seed layer 3 is formed using the processing temperature as a parameter (step 1), and the silicon film 4 is formed on the seed layer 3 with the processing conditions fixed (step 2). The film thickness of the silicon film 4 to be used was compared.
・ Step 1
DIPADS flow rate: 200sccm
Processing time: 1 min
Processing temperature: 350 ℃ → 300 ℃ → 250 ℃ → 200 ℃
Processing pressure: 133 Pa (1 Torr)
・ Step 2
SiH ₄ flow rate: 500 sccm
Deposition time: 10min
Deposition temperature: 510 ℃
Stacking pressure: 53.2 Pa (0.4 Torr)

The result is shown in FIG. FIG. 6 is a diagram showing the relationship between the processing temperature of the seed layer and the film thickness of the silicon film formed on the seed layer.
Normally, it was expected that the effect of the seed layer 3 would be diminished if the processing temperature when forming the seed layer 3 was lowered, but as shown in FIG. 6, a result contrary to the expectation was obtained. .

  As shown in FIG. 6, the film thickness of the silicon film 4 formed on the seed layer 3 is about 6.43 nm when the processing temperature of the seed layer 3 is lowered from 350 ° C. to 300 ° C. To about 6.34 nm. However, when the processing temperature of the seed layer 3 was lowered from 300 ° C. to 250 ° C., the film thickness of the silicon film 4 increased on the contrary. Moreover, the film thickness exceeded about 6.43 nm at a processing temperature of 350 ° C. and reached about 6.61 nm. When the processing temperature of the seed layer 3 is lowered from 250 ° C. to 200 ° C., the film thickness is lowered to about 6.03 nm. Note that the in-plane uniformity of the film thickness varies slightly as large as 8.7% when the processing temperature is 200 ° C., but generally falls within a practical range.

  From the above knowledge, in the formation of the seed layer 3 using a high-order aminosilane-based gas, the optimum temperature range in which silicon can be efficiently adsorbed on the surface to be treated is less than 300 ° C. and more than 200 ° C. It was confirmed to exist between. In order to proceed with this confirmation, the pressure dependence of the film thickness of the silicon film 4 was examined. If it is in the optimum temperature range, the seed layer 3 that is almost completely adsorbed with silicon arranged at high density on the surface to be processed should be formed without depending on the processing pressure. It is assumed that if the seed layer 3 that is almost completely adsorbed is formed, the film thickness of the silicon film 4 formed on the seed layer 3 does not change greatly, that is, there should be no pressure dependence. It is.

[2. Relationship between processing pressure of seed layer 3 and film thickness of silicon film 4]
After setting the processing conditions as follows, the seed layer 3 is formed using the processing pressure as a parameter (step 1), the processing conditions are fixed, and the silicon film 4 is formed on the seed layer 3 (step 2). The thickness of the silicon film 4 to be formed was compared.
・ Step 1
DIPADS flow rate: 200sccm
Processing time: 1 min
Processing temperature: 300 ° C or 250 ° C
Processing pressure: 133 Pa → 66.5 Pa → 13.3 Pa
(1 Torr → 0.5 Torr → 0.1 Torr)
・ Step 2 (No change of conditions)

  The result is shown in FIG. FIG. 7 is a diagram showing the relationship between the processing pressure of the seed layer 3 and the film thickness of the silicon film 4 formed on the seed layer 3.

(A) When the processing time of the seed layer 3 is 1 min and the processing temperature is 300 ° C. As shown in FIG. 7, it was confirmed that the film thickness of the silicon film 4 tends to decrease as the processing pressure decreases. When the processing temperature is 300 ° C. for a processing time of 1 min, the density of silicon arranged on the surface to be processed is low, and it is estimated that the seed layer 3 will not be formed by complete adsorption. . Note that the in-plane uniformity of the film thickness is within a practical range.
(B) When the processing time of the seed layer 3 is 1 min and the processing temperature is 250 ° C. As shown in FIG. 7, the film thickness of the silicon film 4 slightly decreases as the processing pressure decreases, but the processing temperature is 300 ° C. Compared to the case, it was confirmed that the amount of decrease was small and almost flat. From this result, when the processing time of the seed layer 3 is 1 min, the processing temperature is 250 ° C. rather than 300 ° C., silicon is arranged at a higher density on the surface to be processed, and the seed layer 3 is more complete. It is presumed that it will be formed in a state close to adsorption. Note that the in-plane uniformity of the film thickness is within a practical range.

[3. Relationship between processing pressure of seed layer 3 and haze of silicon film 4]
In order to verify whether or not the seed layer 3 is formed in a state close to complete adsorption, the haze of the surface of the silicon film 4 in the above six samples was examined. If silicon is arranged on the surface to be processed at a high density and the seed layer 3 is formed in a state close to complete adsorption, the minute unevenness on the surface of the silicon film 4 formed thereon becomes small and good haze is achieved. Because of the assumption that will be observed.

FIG. 8 is a diagram showing the relationship between the processing pressure of the seed layer 3 and the haze of the surface of the silicon film 4 formed on the seed layer 3.
As shown in FIG. 8, when the processing time of the seed layer 3 was 1 min, a better haze was observed when the processing temperature was 250 ° C. than 300 ° C. This is because when the processing temperature is 250 ° C., as shown in FIG. 9A, the adsorption density of silicon on the surface to be processed per unit time (1 min in this example) increases and the seed layer 3 becomes more It can be in a state close to complete adsorption. As a result, it can be presumed that the surface roughness of the silicon film 4 is improved because the fine irregularities on the surface of the silicon film 4 formed on the seed layer 3 are reduced.

  On the other hand, when the processing temperature is 300 ° C., the haze deterioration is observed as the film thickness of the silicon film 4 decreases. This is because, as the processing pressure is lowered, as shown in FIG. 9B, the silicon adsorption density on the surface to be processed per unit time (1 min in this example) is compared with the case where the processing temperature is 250 ° C. Therefore, it is estimated that the seed layer 3 having a relatively large number of pinholes and gaps is formed.

  As described above, in the treatment using the high-order aminosilane-based gas, in the region where the reaction temperature is an adsorption reaction and the treatment temperature is 350 ° C. or less, it is possible to efficiently adsorb silicon on the surface to be treated. There is a temperature zone. In this example, the processing temperature is less than 300 ° C. and more than 200 ° C.

  Therefore, by performing the treatment using the high-order aminosilane-based gas in the optimum temperature range, it is possible to form an efficient layer, for example, to form a high-quality seed layer 3 at a low temperature in a short time. . Further, among the above optimum temperature range, a particularly preferable temperature range is a processing temperature range of less than 250 ° C. ± 25 ° C.

[4. Relationship between processing time of seed layer 3 and film thickness of silicon film 4]
As described so far, when the seed layer 3 is formed using a high-order aminosilane-based gas, there is an optimum temperature zone for the adsorption of silicon on the surface to be processed in a region where the processing temperature is 350 ° C. or lower. I understood it. If an optimal temperature zone is used, a high-quality seed layer 3 having a high silicon adsorption density can be obtained even in a short processing time. Moreover, it is not greatly influenced by the processing pressure. The optimum temperature range is a processing temperature range of less than 300 ° C. and more than 200 ° C. Above all, if the processing temperature is around 250 ° C. and is within the range of less than 250 ° C. ± 25 ° C., the same advantages as the processing temperature of 250 ° C. can be obtained.

  However, depending on the process, there is a demand for lowering the processing temperature of the seed layer 3 from the range of processing temperature less than 250 ° C. ± 25 ° C. from the viewpoint of lowering the process temperature.

  On the contrary, from the viewpoint of improving the throughput, there is also a demand to increase the processing temperature of the seed layer 3 to be closer to the processing temperature during the film forming process than the processing temperature of less than 250 ° C. ± 25 ° C. This is from the viewpoint of reducing the time required for temperature increase and high temperature by reducing the control range of the processing temperature.

Therefore, the relationship between the processing time of the seed layer 3 and the film thickness of the silicon film 4 was further investigated.
・ Step 1
DIPADS flow rate: 200sccm
Processing time: 1min → 3min → 5min → 10min
Processing temperature: 300 ° C or 250 ° C or 200 ° C
Processing pressure: 133 Pa (1 Torr)
・ Step 2 (No change of conditions)

  The result is shown in FIG. FIG. 10 is a diagram showing the relationship between the processing time of the seed layer 3 and the film thickness of the silicon film 4 formed on the seed layer 3.

<When processing temperature is 300 ° C>
As shown in FIG. 10, the film thickness of the silicon film 4 tends to increase as the processing time of the seed layer 3 is increased from 1 min to 5 min and 10 min.

<When processing temperature is 250 ° C>
As shown in FIG. 10, even if the processing time of the seed layer 3 is increased from 1 min to 3 min, 5 min, and 10 min, the film thickness of the silicon film 4 remains almost flat.

<When processing temperature is 200 ° C>
As shown in FIG. 10, when the processing time of the seed layer 3 is increased from 1 min to 3 min and 10 min, the film thickness of the silicon film 4 tends to increase.

Furthermore, the haze on the surface of the silicon film 4 in the sample of FIG. 10 was examined.
FIG. 11 is a diagram showing the relationship between the processing time of the seed layer 3 and the haze of the surface of the silicon film 4 formed on the seed layer 3.

<When processing temperature is 300 ° C>
As shown in FIG. 11, when the processing time of the seed layer 3 is increased from 1 min to 5 min and 10 min, the haze on the surface of the silicon film 4 tends to be improved.

<When processing temperature is 250 ° C>
As shown in FIG. 11, when the processing time of the seed layer 3 is increased from 1 min to 3 min, 5 min, and 10 min, the haze on the surface of the silicon film 4 tends to improve when the processing time is increased from 1 min to 3 min. It remains almost flat at 3 min, 5 min and 10 min.

<When processing temperature is 200 ° C>
As shown in FIG. 11, when the processing time of the seed layer 3 is increased from 1 min to 3 min and 10 min, the haze on the surface of the silicon film 4 tends to be improved. It should be noted that values that may be difficult in practice appear at processing times of 1 min and 3 min. However, when the processing time exceeds 3 min, the values are restored to practically sufficient values.

  From these results, when the processing temperature is set to 300 ° C. or higher and 350 ° C. or lower, the seed layer 3 having a practically sufficient level can be obtained by setting the processing time of the seed layer 3 to a finite value of 5 min or longer. it can.

  If the processing temperature is 200 ° C. or lower and room temperature (25 ° C.) or higher, the seed layer 3 having a practically sufficient level can be obtained by setting the processing time of the seed layer 3 to a finite value of 3 min or longer. it can.

[Source gas for silicon film 4]
Next, the source gas for the silicon film 4 formed on the seed layer 3 will be described.
A silicon film 4 is formed on the seed layer 3. The film thickness of the silicon film 4 has a minimum practical film thickness. The minimum practical film thickness is a film thickness that does not cause pinholes even when the film thickness is reduced. The minimum film thickness depends on the source gas of the silicon film 4. For example, the source gas is a monosilane gas that does not contain an amino group, or a higher-order silane-based gas that does not contain an amino group and is higher than disilane.

<When the raw material gas of the silicon film 4 is monosilane gas>
FIG. 12 is a drawing-substituting photograph showing a secondary electron image of the surface of the silicon film 4 when the source gas is monosilane. In FIG. 12, when the seed layer 3 is not formed (no seed layer), the seed layer 3 is formed using an aminosilane-based gas containing only one silicon in the molecular formula (aminosilane seed), higher-order aminosilane In the case of forming using a system gas (higher order aminosilane seed), it is shown.

As shown in FIG. 12, when the raw material gas of the silicon film 4 is monosilane gas, the minimum film thickness that can be practically used without the pinhole of the silicon film 4 is
-No seed layer: 15 nm order-Aminosilane seed: 8 nm order-Higher order aminosilane seed: 6 nm order

<When the source gas of the silicon film 4 is a higher order silane-based gas>
FIG. 13 is a drawing-substituting photograph showing a secondary electron image of the surface of the silicon film 4 when the source gas is a higher order silane-based gas.

As shown in FIG. 13, when the source gas of the silicon film 4 is a high-order silane-based gas, for example, disilane, the minimum film thickness that can be practically used without the pinhole of the silicon film 4 is
-No seed layer: 4 nm order-Aminosilane seed: 3 nm order-Higher order aminosilane seed: 2 nm order

  As shown in FIGS. 12 and 13, when it is desired to reduce the thickness of the silicon film 4, the source gas of the silicon film 4 is preferably a higher-order silane-based gas of disilane or higher. Of course, when a thick film is required for the silicon film 4, monosilane gas can be used. In the process, for example, when pinholes are allowed, when the source gas of the silicon film 4 is a higher order silane gas, the film thickness of the silicon film 4 is set to a finite value of less than 2 nm, and silicon When the raw material gas for the film 4 is monosilane gas, the film thickness of the silicon film 4 can be set to a finite value of less than 6 nm. In these cases, pinholes will be generated, but the advantage of improving the surface roughness can be obtained as compared with the case without the seed layer.

  In this way, depending on the film thickness required for the silicon film 4, the source gas of the silicon film 4 is a monosilane gas that does not contain an amino group, or a higher-order silane-based gas that does not contain an amino group and is higher than disilane. Is preferably selected.

As higher-order silane-based gas that does not contain amino groups and is higher than disilane,
Disilane (Si ₂ H ₆ ),
Si hydride represented by the formula Si _m H _{2m + 2} (where m is a natural number of 3 or more) Si _n H _2n (where n is a natural number of 3 or more) A gas containing one can be selected.

Further, a hydride of silicon represented by the formula of Si _m H _{2m + 2} (where m is a natural number of 3 or more)
Si ₃ H ₈
Si ₄ H ₁₀
Si ₅ H ₁₂
Si ₆ H ₁₄
Si ₇ H ₁₆
You can choose from at least one of the following.

Further, a hydride of silicon represented by the formula of Si _n H _2n (where n is a natural number of 3 or more)
Si ₃ H ₆
Si ₄ H ₈
Si ₅ H ₁₀
Si ₆ H ₁₂
Si ₇ H ₁₄
You can choose from at least one of the following.

  Also, from the results shown in FIGS. 12 and 13, it can be understood that it is preferable to form the silicon film 4 rather than not to form the seed layer 3. This is because the generation of pinholes in the silicon film 4 can be suppressed. Further, as the processing gas used for forming the seed layer 3, a higher-order aminosilane-based gas containing two or more silicons in the molecular formula may be used rather than an aminosilane-based gas containing only one silicon in the molecular formula. It can also be understood that it is preferable. This is because the generation of pinholes in the silicon film 4 can be further suppressed.

(Second Embodiment)
In the first embodiment, when it is desired to reduce the thickness of the silicon film formed on the seed layer 3, the source gas is selected from higher silane-based gases that do not contain amino groups and that are disilane or higher. Explained that it was good.

  In the second embodiment, when the source gas of the silicon film formed on the seed layer 3 is selected from higher-order silane-based gas (hereinafter abbreviated as higher-order silane-based gas) that does not contain an amino group and is not less than disilane. It is related with the application example suitable for.

<Application Example 1: Multiple seed layer>
When the raw material gas for the silicon film formed on the seed layer 3 is a high order silane-based gas, the silicon film in which the generation of pinholes is suppressed can be formed thin. This is effective when the seed layer 3 is a multiple seed layer.

  FIG. 14 is a flowchart showing an example of a sequence according to application example 1 of the silicon film forming method according to the second embodiment of the present invention, and FIGS. 15A to 15D are sequences shown in FIG. It is sectional drawing which shows schematically the state of the to-be-processed object in it.

  First, an object to be processed illustrated in FIG. 15A, for example, the silicon substrate 1 is carried into a processing chamber of a film formation apparatus. The object to be processed shown in FIG. 15A is the same as the object to be processed shown in FIG. 2A, and a silicon oxide film 2 is formed on the silicon substrate 1. The surface of the silicon oxide film 2 becomes a surface to be processed on which a silicon film is formed. In addition, the substance which comprises a to-be-processed surface is not restricted to the silicon oxide film 2 similarly to 1st Embodiment.

  Next, as shown in FIGS. 14 and 15B, silicon is adsorbed on the surface (surface to be processed) of the silicon oxide film 2 to form the seed layer 3. As in the first embodiment, the seed layer 3 is formed by supplying a high-order aminosilane-based gas on the surface of the silicon oxide film 2 as a processing gas, and processing for forming the seed layer 3 is performed. The temperature is 350 ° C. or lower and room temperature (25 ° C.) or higher (step 1). As the higher-order aminosilane-based gas, those described in Step 1 of the first embodiment can be selected. In this example, DIPADS was used. The processing conditions may also be the conditions described in step 1 of the first embodiment.

Next, as shown in FIGS. 14 and 15C, silicon is deposited on the seed layer 3 to form a second seed layer 3a (step 3). The second seed layer 3a is formed by supplying, as a processing gas, a higher-order silane-based gas of disilane or higher that does not contain an amino group on the surface of the seed layer 3. In this example, disilane was used as the processing gas for the second seed layer 3a. As shown in FIG. 13, the film thickness of the second seed layer 3a may be in the vicinity of the minimum film thickness at which the generation of pinholes is suppressed, for example, in the range of 2 nm order to 4 nm order. In this example, the film thickness is on the order of 2 nm (2 nm or more and less than 3 nm). For example, the deposition time may be adjusted so that the film thickness of the second seed layer 3a is on the order of 2 nm. An example of the processing conditions in Step 3 is
Si ₂ H ₆ flow rate: 300 sccm
Deposition time: 16min
Deposition temperature: 400 ℃
Stacking pressure: 133 Pa (1 Torr)
It is. However, in the process, for example, when pinholes are allowable, the film thickness of the second seed layer 3a does not need to be set to 2 nm or more and 4 nm or less, and can be a finite value of 4 nm or less.

Next, as shown in FIGS. 14 and 15D, silicon is deposited on the second seed layer 3a to form a silicon film 4 (step 4). The silicon film 4 is formed by supplying a silane-based gas not containing an amino group as a processing gas on the surface of the second seed layer 3a. As the silane-based gas not containing an amino group, the gas described in Step 2 of the first embodiment can be selected. In this example, monosilane was used. The processing conditions may also be the conditions described in step 2 of the first embodiment. The formed silicon film 4 is, for example, amorphous silicon. Of course, as the processing gas for the silicon film 4, a higher-order silane-based gas containing no amino group or higher than disilane can be used. In this case, the higher-order silane-based gas higher than disilane not containing an amino group is less than or equal to the higher-order silane-based gas higher than disilane not containing an amino group used as the processing gas for the second seed layer 3a. It is preferable to use a silane-based gas. For example, when disilane (Si ₂ H ₆ ) is used as the processing gas for the second seed layer 3 a, disilane (Si ₂ H ₆ ) or monosilane (SiH ₄ ) is used as the processing gas for the silicon film 4. Is preferred. For example, when trisilane (Si ₃ H ₈ ) is used as the processing gas for the second seed layer 3 a, the processing gas for the silicon film 4 is trisilane (Si ₃ H ₈ ) or disilane (Si ₂ H _6). ) Or monosilane (SiH ₄ ) is preferably used.

  As described above, when a silicon film is formed on the seed layer 3 by deposition (vapor phase growth) or adsorption using a high-order silane-based gas not containing an amino group, the silicon film is included in the multiple seed layers. In this example, it can be applied as the second seed layer 3a. This is because the generation of pinholes can be suppressed even when the formed silicon film is thin.

  According to the second embodiment, the thin second seed layer 3a having a thin film thickness, no pinholes and excellent flatness can be formed on the seed layer 3 by deposition or adsorption. . For this reason, it is possible to obtain an advantage that the silicon film 4 having excellent flatness can be formed by deposition on the second seed layer 3a.

<Application Example 2: Multiple Seed Layer + Example of Filling Hole or Groove>
Application example 2 relates to a sequence in which a silicon film is formed on the multiple seed layer shown in application example 1, and holes or grooves are filled with the silicon film.

  16 (A) to 16 (F) are cross sections schematically showing the state of the object to be processed in an example of a sequence according to application example 2 of the silicon film forming method according to the second embodiment of the invention. FIG.

  First, as shown in FIG. 16A, a silicon oxide film 2 is formed on a silicon substrate 1. In the silicon oxide film 2, holes or grooves 5 reaching the silicon substrate 1 from the surface are formed. In this example, the seed layer 3 is formed on the object to be processed having such a structure.

  Next, as shown in FIG. 16B, a seed layer is formed on the surface (surface to be processed) of the silicon oxide film 2 having holes or grooves 5 according to the method described in the first and second embodiments. 3 is formed.

  Next, as shown in FIG. 16C, a second seed layer 3a is formed on the seed layer 3 according to the method described in the second embodiment. Thereby, a multiple seed layer is formed. Each of the seed layer 3 and the second seed layer 3a is preferably formed non-doped. This is from the viewpoint of maintaining the flatness of the surface of the multiple seed layer including the seed layer 3 and the second seed layer 3a. That is, if the seed layer 3 and the second seed layer 3a are formed while doping with impurities serving as donors or acceptors, for example, arsenic, phosphorus, and boron, the flatness of the surface of the multiple seed layer may be impaired. This possibility can be eliminated by forming the seed layer 3 and the second seed layer 3a non-doped.

  When the seed layer 3 and the second seed layer 3a are formed non-doped, as shown in FIG. 17, after forming the seed layer 3 and the second seed layer 3a, for example, a donor or You may make it dope the impurity used as an acceptor. After the seed layer 3 and the second seed layer 3a are thus formed non-doped, impurities such as arsenic, phosphorus, and boron, for example, arsenic, phosphorus, and boron are doped by a vapor phase diffusion method to form the surface of the multiple seed layer. The resistance value of the multiple seed layer can be lowered while maintaining good flatness.

  Next, as shown in FIG. 16D, a silane-based gas not containing an amino group is supplied onto the multiple seed layer including the seed layer 3 and the second seed layer 3a, and silicon is deposited on the multiple seed layer. Thus, the silicon film 4 is formed. At this time, the silicon film 4 is formed with a film thickness that does not block the hole or groove 5 while leaving the opening 6 corresponding to the hole or groove 5. Although it is a silane-based gas not containing an amino group at this time, either a monosilane gas or a higher-order silane gas higher than disilane can be selected, but considering the good step coverage, a monosilane gas can be selected. Good. This is because the silicon film formed using the monosilane gas as the source gas tends to improve the step coverage when the hole or the groove 5 is covered as compared with, for example, the silicon film formed using the disilane gas as the source gas.

  Next, as shown in FIG. 16E, the silicon film 4 is etched while remaining along the hole or groove 5 to widen the opening 6 corresponding to the hole or groove 5 in the silicon film 4. In this example, the silicon film 4 is etched so that the cross section is V-shaped. In this specification, this is called V-shaped etching.

  Note that the silicon film 4 is also preferably formed non-doped similarly to the seed layer 3 and the second seed layer 3a. This is from the viewpoint of maintaining the flatness of the surface of the silicon film 4. In the case where the silicon film 4 is formed non-doped, as shown in FIG. 18, after the silicon film 4 is etched as shown in FIG. 16E, for example, an impurity that becomes a donor or an acceptor by a vapor phase diffusion method You may make it dope. Thus, after forming the silicon film 4 non-doped and etching, the resistance value of the silicon film 4 is lowered by doping a dopant or an acceptor, for example, arsenic, phosphorus, or boron by a vapor phase diffusion method. Can do.

  Next, as shown in FIG. 16F, a thin film 7 for embedding the opening 6 is formed on the silicon film 4 with the opening 6 widened. The thin film 7 may be a silicon film or a thin film other than a silicon film, for example, a metal film.

  As described above, the second embodiment can be applied to an embedding sequence for filling holes or grooves formed in the surface to be processed, in this example, holes or grooves 5 formed in the silicon oxide film 2. .

<V-shaped etching: aspect ratio dependency>
By the way, the cross-sectional shape of the silicon film 4 after the V-shaped etching shown in FIG. 16 (E) in the hole or groove 5 is the hole of the silicon film 4 after the deposition step shown in FIG. 16 (D). Alternatively, it was confirmed that there is a relationship with the aspect ratio of the opening 6 corresponding to the groove 5.

To explain this relationship, the term “etching coverage” is defined.
FIGS. 19A to 19C are cross-sectional views for explaining the definition of “etching coverage”.

  FIG. 19A is a cross-sectional view of the initial state. In the initial state, for example, it is assumed that the silicon film 4 having a top film thickness of 25 nm and a bottom film thickness of 25 nm is formed. After this is etched, it is assumed that the top film thickness is 5 nm and the bottom film thickness is 5 nm, respectively, as shown in FIG. 19B. This state is set to etching coverage = 0%. Further, as shown in FIG. 19C, after etching, the top film thickness is etched to 5 nm, and the bottom film thickness remains 25 nm. This state is etching coverage = 100%.

  20A is a sectional view showing the initial state of the hole or groove 5, and FIG. 20B is a case where the aspect ratio of the opening 6 corresponding to the hole or groove 5 of the silicon film 4 is “37.5”. FIG. 20C is a cross-sectional view showing a case where the aspect ratio is “12”, and FIG. 21 is a view showing a relationship between the aspect ratio and etching coverage.

  As shown in FIG. 21, when the aspect ratio of the opening 6 is “12”, the etching coverage is about 27%. On the other hand, when the aspect ratio of the opening 6 is “37.5”, the etching coverage is about 89%. When these points are placed on a straight line, the etching coverage approaches about 0% when the aspect ratio is 0 (that is, a plane).

  As described above, the aspect ratio of the opening 6 corresponding to the hole or groove 5 of the silicon film 4 after the deposition step shown in FIG. This is related to the cross-sectional shape of the silicon film 4 in the hole or groove 5.

  That is, when it is desired to control the cross-sectional shape of the silicon film 4 in the hole or groove 5 after V-shaped etching so as to become narrower toward the bottom of the hole or groove 5 (to make the etching coverage close to 100%), the opening The aspect ratio of the part 6 should be increased. This is because as the aspect ratio of the opening 6 increases, the etching gas becomes less likely to enter the depth of the opening 6, and as a result, the cross-sectional shape of the silicon film 4 approaches 100% of the etching coverage. .

  As described above, by controlling the aspect ratio of the opening 6 after the silicon film 4 is formed, the cross-sectional shape of the silicon film 4 in the hole or groove 5 after the V-shaped etching can be controlled. . As a result of controlling the cross-sectional shape in this way, the etching coverage after the V-shaped etching is close to 100%, and the thin film 7 can provide the advantage that the opening 6 that is easier to fill can be obtained.

<Application Example 3: Multiple Seed Layer + Other Example of Filling Hole or Groove>
Application example 3 relates to another sequence in which a silicon film is formed on the multiple seed layer shown in application example 1, and holes or grooves are filled with the silicon film.

  22 (A) to 22 (I) are cross-sectional views schematically showing the state of the object to be processed in an example of a sequence according to application example 3 of the silicon film forming method according to the second embodiment of the present invention. FIG.

  First, as shown in FIGS. 22A to 22C, the second seed layer 3a according to the application example 2 according to the method described with reference to FIGS. 16A to 16C. Form. Also in this example, the seed layer 3 and the second seed layer 3a are preferably formed undoped, and when formed undoped, as shown in FIG. 23, for example, a donor or acceptor is formed by a vapor phase diffusion method. The seed layer 3 and the second seed layer 3a may be doped with impurities that become

  Next, as shown in FIG. 22D, a silane-based gas not containing an amino group is supplied onto the multiple seed layer including the seed layer 3 and the second seed layer 3a, and silicon is deposited on the multiple seed layer. Thus, the silicon film 4 is formed. In this example, the step coverage of the silicon film 4 does not matter so much. Therefore, the hole or groove 5 may be blocked on the way.

  Next, as shown in FIG. 22E, the silicon film 4, the seed layer 3, and the second seed layer 3 a are etched to leave the silicon film 4 at the bottom of the hole or groove 5.

  Also in this example, the silicon film 4 is preferably formed non-doped. In the case of being formed non-doped, as shown in FIG. 24, for example, after etching, an impurity that becomes a donor or an acceptor is etched by a vapor phase diffusion method. The silicon film 4 may be doped.

  Next, as shown in FIG. 22F, the steps shown in FIGS. 22B and 22C are repeated to form the seed layer 3 and the second seed layer 3a again.

  Next, as shown in FIG. 22G, the silicon film 4 is formed again by repeating the process shown in FIG. After that, as shown in FIG. 22 (H), the process shown in FIG. 22 (E) is repeated to etch the silicon film 4, the seed layer 3 and the second seed layer 3a, and at the bottom of the hole or groove 5, The silicon film 4 is left.

  Thereafter, the steps shown in FIGS. 22B to 22E are repeated the number of times designed, thereby filling the holes or grooves 5 with the silicon film 4 as shown in FIG.

  As described above, in the second embodiment, a hole or groove formed in the surface to be processed, in this example, a hole or groove 5 formed in the silicon oxide film 2, is formed into a multiple seed layer, and the silicon film 4 is formed. It can also be applied to an embedding sequence in which deposition and etching are repeatedly performed.

In the example shown in FIGS. 22A to 22I,
-Formation of multiple seed layer including seed layer 3 and second seed layer 3a-Formation of silicon film 4-Three steps of etching of silicon film 4 and multiple seed layer were repeated the number of times designed.

However, as shown in FIGS. 25A to 25D, “the formation of a multiple seed layer including the seed layer 3 and the second seed layer 3a” is limited to the first first layer and the second and subsequent layers. Is
Formation of the silicon film 4 It is possible to repeat the two steps of etching the silicon film 4 a number of times designed.

<Application Example 4: Doping to second seed layer and silicon film>
In the second embodiment, when the second seed layer 3a and the silicon film 4 are doped with an impurity serving as a donor or acceptor, as shown in FIGS. 26A and 27A, a source gas (treatment) Gas), the non-doped second seed layer 3a and the silicon film 4 are formed, and then the non-doped second seed layer 3a and the silicon film 4 are formed on the non-doped second seed layer 3a and the silicon film 4 as shown in FIGS. On the other hand, a doping gas containing donors or acceptors, for example, arsenic, phosphorus and boron, is supplied, and these impurities are doped into the non-doped second seed layer 3a and the silicon film 4 by vapor phase diffusion. Was preferred. This is because it is possible to obtain an advantage that the resistance value can be lowered while maintaining good flatness on each of the surfaces of the second seed layer 3a (multiple seed layer) and the silicon film 4.

  However, depending on the process, some degree of surface roughness may be acceptable. In this case, as shown in FIGS. 28 and 29, the source gas (processing gas) and the doping gas may be simultaneously supplied to form the second seed layer 3a and the silicon film 4 doped with the impurities. Is possible. During the formation of the seed layer 3, the source gas (processing gas) and the doping gas may or may not be supplied simultaneously. That is, in the step of forming the multiple seed layer including the seed layer 3 and the second seed layer 3a, if the source gas (processing gas) and the doping gas are supplied at least during the formation of the second seed layer 3a. Good.

  Examples of the dope shown in FIGS. 28 and 29 include, for example, FIGS. 16 (A) to 16 (F), FIGS. 22 (A) to 22 (I), and FIGS. 25 (A) to 25 (A). This is effective in the process of filling the hole or groove 5 described with reference to D) with the silicon film 4. In such a process, the surface at the time of deposition may eventually be retreated, for example, by etching or polishing. For this reason, the accuracy of the strict surface roughness may not be required. An example of the final shape of the silicon film 4 in the process shown in FIGS. 16A to 16F is shown in FIG. 30A, and the silicon film in the process shown in FIGS. 22A to 22I. An example of the final shape 4 is shown in FIG. 30B, and an example of the final shape of the silicon film 4 in the process shown in FIGS. 25A to 25D is shown in FIG.

(Third embodiment)
Next, an example of a film forming apparatus capable of executing the silicon film forming method according to the first and second embodiments of the present invention will be described as a third embodiment of the present invention.

<Deposition system>
FIG. 31 is a sectional view schematically showing an example of a film forming apparatus according to the third embodiment of the present invention.

  As shown in FIG. 31, the film forming apparatus 100 includes a cylindrical processing chamber 101 having a ceiling with a lower end opened. The entire processing chamber 101 is made of, for example, quartz. A quartz ceiling plate 102 is provided on the ceiling in the processing chamber 101. For example, a manifold 103 formed in a cylindrical shape from stainless steel is connected to a lower end opening of the processing chamber 101 via a seal member 104 such as an O-ring.

  The manifold 103 supports the lower end of the processing chamber 101. From the lower side of the manifold 103, a plurality of, for example, 50 to 100 semiconductor substrates as processing objects, in this example, a quartz wafer boat 105 on which the silicon substrates 1 can be placed in multiple stages are placed in the processing chamber 101. It can be inserted. Thereby, the silicon substrate 1 is accommodated in the processing chamber 101. The wafer boat 105 has a plurality of columns 106, and a plurality of silicon substrates 1 are supported by grooves formed in the columns 106.

  The wafer boat 105 is placed on a table 108 via a quartz heat insulating cylinder 107. The table 108 is supported on a rotating shaft 110 that opens and closes a lower end opening of the manifold 103 and penetrates a lid portion 109 made of, for example, stainless steel. For example, a magnetic fluid seal 111 is provided in the penetrating portion of the rotating shaft 110 and supports the rotating shaft 110 so as to be rotatable while hermetically sealing. Between the peripheral part of the cover part 109 and the lower end part of the manifold 103, for example, a seal member 112 made of an O-ring is interposed. Thereby, the sealing performance in the processing chamber 101 is maintained. The rotating shaft 110 is attached to the tip of an arm 113 supported by an elevating mechanism (not shown) such as a boat elevator, for example. As a result, the wafer boat 105, the lid portion 109, and the like are integrally moved up and down and inserted into and removed from the processing chamber 101.

  The film forming apparatus 100 includes a processing gas supply mechanism 114 that supplies a gas used for processing in the processing chamber 101, and an inert gas supply mechanism 115 that supplies an inert gas in the processing chamber 101. .

The processing gas supply mechanism 114 of this example includes an aminosilane-based gas supply source 117a (hereinafter abbreviated as aminosilane-based gas supply source 117a) that includes two or more silicons in the molecular formula, and a silane-based gas supply source 117b that does not include an amino group. (Hereinafter abbreviated as silane-based gas supply source 117b). The inert gas supply mechanism 115 includes an inert gas supply source 120. An example of an aminosilane-based gas containing two or more silicons in the molecular formula is DIPADS, and an example of a silane-based gas not containing an amino group is Si ₂ H ₆ . An example of the inert gas is nitrogen gas. The inert gas is used as a purge gas.

  The aminosilane-based gas supply source 117a is connected to the dispersion nozzle 123a via the flow rate controller 121a and the on-off valve 122a. Similarly, the silane-based gas supply source 117b is connected to the dispersion nozzle 123b via the flow rate controller 121b and the on-off valve 122b.

  In addition, when supplying dopant gas with the silane type gas which does not contain an amino group, as shown in FIG. 32, what is necessary is just to provide the dopant gas supply source 117c in the process gas supply mechanism 114 further. The dopant gas supply source 117c is connected to the dispersion nozzle 123a via the flow rate controller 121d and the on-off valve 122d.

  The dispersion nozzles 123a and 123b are made of quartz tubes, penetrate the sidewalls of the manifold 103 inward, are bent upward, and extend vertically. A plurality of gas discharge holes 124 are formed at predetermined intervals in vertical portions of the dispersion nozzles 123a and 123b. As a result, each gas is ejected from the gas ejection holes 124 in the horizontal direction into the processing chamber 101 substantially uniformly.

  The inert gas supply source 120 is connected to the nozzle 128 via the flow rate controller 121c and the on-off valve 122c. The nozzle 128 passes through the side wall of the manifold 103 and discharges an inert gas from the tip thereof into the processing chamber 101 in the horizontal direction.

  An exhaust port 129 for exhausting the inside of the processing chamber 101 is provided in a portion of the processing chamber 101 opposite to the dispersion nozzles 123a and 123b. The exhaust port 129 is formed in an elongated shape by scraping the side wall of the processing chamber 101 in the vertical direction. An exhaust port cover member 130 having a U-shaped cross section so as to cover the exhaust port 129 is attached to a portion corresponding to the exhaust port 129 of the processing chamber 101 by welding. The exhaust port cover member 130 extends upward along the side wall of the processing chamber 101, and defines a gas outlet 131 above the processing chamber 101. An exhaust mechanism 132 including a vacuum pump or the like is connected to the gas outlet 131. The exhaust mechanism 132 exhausts the inside of the processing chamber 101 to set the exhaust of the processing gas used for the processing and the pressure in the processing chamber 101 to a processing pressure corresponding to the processing.

  A cylindrical heating device 133 is provided on the outer periphery of the processing chamber 101. The heating device 133 activates the gas supplied into the processing chamber 101 and heats the target object accommodated in the processing chamber 101, in this example, the silicon substrate 1.

  Control of each part of the film forming apparatus 100 is performed by a controller 150 including, for example, a microprocessor (computer). Connected to the controller 150 is a user interface 151 including a touch panel on which an operator inputs commands to manage the film forming apparatus 100, a display for visualizing and displaying the operating status of the film forming apparatus 100, and the like. Yes.

  A storage unit 152 is connected to the controller 150. The storage unit 152 is a control program for realizing various processes executed by the film forming apparatus 100 under the control of the controller 150, and for causing each component of the film forming apparatus 100 to execute processes according to the processing conditions. A program or recipe is stored. The recipe is stored in a storage medium in the storage unit 152, for example. The storage medium may be a hard disk or a semiconductor memory, or a portable medium such as a CD-ROM, DVD, or flash memory. Moreover, you may make it transmit a recipe suitably from another apparatus via a dedicated line, for example. The recipe is read from the storage unit 152 according to an instruction from the user interface 151 as necessary, and the controller 150 executes processing according to the read recipe. A desired process is performed under the control of 150.

  In this example, under the control of the controller 150, the film formation process according to the silicon film formation method according to the first embodiment or the silicon film formation method according to the second embodiment is sequentially performed. To be implemented.

  The silicon film forming methods according to the first and second embodiments can be implemented by a single film forming apparatus by using a film forming apparatus 100 as shown in FIG.

  Further, the film forming apparatus is not limited to the batch type as shown in FIG. 31, but may be a single wafer type film forming apparatus.

  As described above, the present invention has been described according to the embodiment. However, the present invention is not limited to the above embodiment and can be variously modified.

In the above-described embodiment, the object to be processed is the silicon substrate 1, but the object to be processed is not limited to the silicon substrate 1, and a method for manufacturing an electronic product in which progress in miniaturization is progressing, for example, a semiconductor device In addition to the manufacturing process, it can be suitably used for a manufacturing process of a flat panel display.
In addition, the present invention can be variously modified without departing from the gist thereof.

  DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Silicon oxide film, 3 ... Seed layer, 3a ... 2nd seed layer, 4 ... Silicon film, 5 ... Hole or groove, 6 ... Opening, 7 ... Thin film.

Claims (14)

A silicon film forming method for forming a silicon film on an object to be processed having holes or grooves on a surface to be processed,
(1) supplying a high-order aminosilane-based gas containing two or more silicons in a molecular formula on the surface to be processed, and adsorbing silicon on the surface to be processed to form a first seed layer;
(2) On the first seed layer, a high-order silane-based gas containing two or more silicons in the molecular formula and not containing amino groups is supplied, and silicon is deposited on the first seed layer to form a second seed. Forming a layer;
(3) supplying a silane-based gas not containing an amino group on the second seed layer and depositing silicon on the second seed layer to form a silicon film;
(4) etching the silicon film to leave the silicon film at the bottom of the hole or groove;
With
The steps (1) to (4) are repeated, and the holes or grooves on the surface to be processed are filled with the silicon film formed repeatedly,
A method for forming a silicon film, characterized in that the processing temperature in the step (1) is in the range of 350 ° C. or lower and room temperature (25 ° C.) or higher. The first seed layer is formed by adsorbing silicon on the processing surface without vapor-depositing silicon on the processing surface,
2. The method of forming a silicon film according to claim 1, wherein the adsorption density of the silicon is controlled by adjusting a processing temperature in the step (1).   3. The method for forming a silicon film according to claim 1, wherein the processing temperature in the step (1) is in a range of less than 300 ° C. and more than 200 ° C. 4.   3. The method of forming a silicon film according to claim 1, wherein the processing temperature in the step (1) is set to a range of less than 250 ° C. ± 25 ° C. 4.   2. The process according to claim 1, wherein when the step (1) is performed at a temperature of less than 200 ° C. and a room temperature (25 ° C.) or more, the processing time in the step (1) is a finite time exceeding 3 min. The method for forming a silicon film according to claim 2.   6. The method of forming a silicon film according to claim 1, wherein the second seed layer is formed by vapor-depositing silicon on the seed layer.   7. The method of forming a silicon film according to claim 1, wherein the thickness of the second seed layer is a finite value of 4 nm or less. The silane-based gas containing no amino group used in the step (3) is
Wherein (2) from claim 1, wherein the relative order silane-based gas containing no amino group used in advance process is homogeneous the following silane-based gas to one of the claims 7 The silicon film formation method described. The silane gas having the same or lower order is
SiH ₄ or Si ₂ H ₆
The method for forming a silicon film according to claim 8 , wherein: When forming the first seed layer and the second seed layer, at least during the formation of the second seed layer, a source gas and a doping gas containing an impurity serving as a donor or an acceptor are simultaneously supplied. The method for forming a silicon film according to any one of claims 1 to 9 . After the step (2),
(5) The method according to any one of claims 1 to 9 , further comprising a step of doping the first seed layer and / or the second seed layer with an impurity serving as a donor or an acceptor. The silicon film formation method described. Wherein (3) in step, any one of claims 1 to 11, characterized by supplying a silane-based gas not including the amino group, and a doping gas containing an impurity serving as a donor or acceptor simultaneously 2. A method for forming a silicon film according to 1. After the step (4),
(6) The method according to any one of claims 1 to 11 , further comprising a step of doping an impurity serving as a donor or an acceptor into the silicon film remaining at the bottom of the hole or groove. The silicon film formation method described. Doping of said impurity, the process of manufacturing a film according to claim 11 or claim 13 characterized in that it is performed by a vapor diffusion method.