JP2014222777A - Method for forming amorphous silicon film and film forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for forming an amorphous silicon film capable of further improving accuracy of surface roughness and corresponding to progress in miniaturization of a contact hole and a line and the like.SOLUTION: A method for depositing an amorphous silicon film successively performs the following steps in a processing chamber: housing a substrate 1 in the processing chamber; heating the substrate in the processing chamber; adjusting pressure by evacuating the inside of the processing chamber; forming a seed layer 3 on the substrate by supplying an aminosilane-based gas to the processing chamber and having the aminosilane-based gas adsorbed under a condition that the aminosilane-based gas is not thermally decomposed and; forming an amorphous silicon film 4 on the seed layer 3 by supplying a silane-based gas not including an amino group into the processing chamber under a condition that the silane-based gas not including an amino group is thermally decomposed; forming the seed layer 3; and forming the amorphous silicon film 4.

Description

  The present invention relates to an amorphous silicon film forming method and a film forming apparatus.

  Amorphous silicon is used for embedding contact holes and lines in semiconductor integrated circuit devices. A method for forming an amorphous silicon film is described in, for example, Patent Documents 1 and 2. In particular, Patent Document 2 describes a method of obtaining a conductor layer having a smooth surface by decomposing disilane at 400 to 500 ° C.

  Recently, with the miniaturization of semiconductor integrated circuit devices, the requirement for filling contact holes and lines has become increasingly severe.

JP-A 63-29954 Japanese Unexamined Patent Publication No. 1-221756

  However, if amorphous silicon using disilane is used to fill contact holes and lines that have been miniaturized, the amorphous silicon after film formation has poor coverage at the contact hole, and large voids are generated. End up. 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. Another factor is the poor accuracy of surface roughness.

  The present invention has been made in view of the above circumstances, and provides an amorphous silicon film forming method and apparatus capable of further improving the accuracy of surface roughness and adapting to the progress of miniaturization of contact holes and lines. provide.

  A method for forming an amorphous silicon film according to a first aspect of the present invention includes a step of accommodating a substrate in a processing chamber, a step of heating the substrate in the processing chamber, and exhausting the processing chamber to adjust the pressure. A step of supplying an aminosilane-based gas into the processing chamber under conditions where the aminosilane-based gas is not thermally decomposed to adsorb the aminosilane-based gas to form a seed layer on the substrate; A step of forming an amorphous silicon film on the seed layer by supplying a silane-based gas containing no amino group into the processing chamber under a condition in which the silane-based gas is thermally decomposed; and a step of forming the seed layer; The step of forming the amorphous silicon film is continuously performed in the processing chamber.

  An amorphous silicon film forming apparatus according to a second aspect of the present invention includes a processing chamber for storing and processing a substrate, heating means for heating the substrate stored in the processing chamber, and a processing chamber. An aminosilane-based gas supply means for supplying an aminosilane-based gas; a silane-based gas supply means for supplying a silane-based gas not containing an amino group in the processing chamber; and an exhaust means for exhausting the processing chamber; A controller for controlling the heating means, the aminosilane-based gas supply means, the silane-based gas supply means not containing the amino group, and the exhaust means, wherein the controller thermally decomposes the aminosilane-based gas on the substrate. The aminosilane-based gas is adsorbed by heating to a temperature at which it is not heated and supplying the aminosilane-based gas into the processing chamber. A step of forming a seed layer; and a step of thermally decomposing the silane-based gas not containing the amino group to form an amorphous silicon film by supplying the silane-based gas not containing the amino group into the processing chamber; The heating means, the aminosilane-based gas supply means, so that the step of forming the seed layer and the step of forming the amorphous silicon layer subsequent thereto are continuously performed in the same processing chamber. The silane-based gas supply means not containing the amino group and the exhaust means are controlled.

  According to the present invention, it is possible to provide a method and apparatus for forming an amorphous silicon film that can further improve the accuracy of surface roughness and can cope with the progress of miniaturization of contact holes and lines.

A flow chart showing an example of a sequence of an amorphous silicon film deposition method according to an embodiment of the present invention Cross-sectional view schematically showing the state of the sample in the sequence Diagram showing the relationship between deposition time and amorphous silicon film thickness Diagram showing the relationship between deposition time and amorphous silicon film thickness The enlarged view which expanded the inside of the broken-line frame A in FIG. The enlarged view which expanded the inside of the broken-line frame B in FIG. Photo substitute for drawing showing secondary electron image of surface and cross section of amorphous silicon film Photo substitute for drawing showing secondary electron image of surface and cross section of amorphous silicon film Photo substitute for drawing showing secondary electron image of surface and cross section of amorphous silicon film Photo substitute for drawing showing secondary electron image of surface and cross section of amorphous silicon film The figure which shows the relationship between the film thickness of an amorphous silicon film, and the average surface roughness Ra of the amorphous silicon film surface Diagram showing the relationship between the thickness of the amorphous silicon film and the haze of the amorphous silicon film surface Sectional drawing which shows the structural example of the contact hole formed in the interlayer insulation film Enlarged view corresponding to broken line circle C in FIG. Sectional drawing which shows roughly an example of the film-forming apparatus which can implement the film-forming method of the amorphous silicon film concerning one Embodiment of this invention

  The inventors of the present application speculated that the surface roughness of the amorphous silicon film may be related to the incubation time of the amorphous silicon film. It is assumed that the longer the incubation time, the more easily the size of the nuclei varies, which affects the accuracy of the surface roughness of the amorphous silicon where deposition begins after the nucleation.

  However, there is no known method for shortening the incubation time of the amorphous silicon film.

  As described below, the present inventors succeeded in shortening the incubation time of the amorphous silicon film, and as a result, succeeded in further improving the accuracy of the surface roughness of the amorphous silicon film.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Note that common parts are denoted by common reference numerals throughout the drawings.

  Note that in this specification, amorphous silicon is not a term indicating only amorphous silicon, but amorphous silicon, and nanocrystalline silicon in which amorphous to nano-sized crystal grains that can achieve the surface roughness accuracy disclosed in this specification are collected. And a term including all of silicon in which the amorphous silicon and the nanocrystalline silicon are mixed.

  FIG. 1 is a flowchart showing an example of a sequence of a method for forming an amorphous silicon film according to an embodiment of the present invention, and FIGS. 2A to 2C are cross-sectional views schematically showing a state of a sample in the sequence.

  First, a sample (see FIG. 2A) in which a base 2 having a thickness of about 100 nm is formed on a semiconductor substrate, for example, a silicon substrate 1 shown in FIG. 2A is carried into a processing chamber of a film forming apparatus. Examples of the base 2 are a silicon oxide film and a silicon nitride film.

  Next, as shown in FIGS. 1 and 2B, a seed layer 3 is formed on the surface of the base 2. In this example, the seed layer 3 is formed on the surface of the base 2 by heating the base 2 and flowing an aminosilane-based gas over the surface of the heated base 2 (step 1).

Examples of aminosilane gases include
BAS (Butylaminosilane)
BTBAS (Bicter Shaftybutylaminosilane)
DMAS (dimethylaminosilane)
BDMAS (Bisdimethylaminosilane)
TDMAS (trisdimethylaminosilane),
DEAS (diethylaminosilane),
BDEAS (bisdiethylaminosilane),
DPAS (dipropylaminosilane),
DIPAS (Diisopropylaminosilane)
Etc. In this example, DIPAS was used.

An example of the processing conditions in Step 1 is
DIPAS flow rate: 500sccm
Processing time: 5 min
Processing temperature: 400 ℃
Processing pressure: 53.2 Pa (0.4 Torr)
It is. The process of step 1 is hereinafter referred to as preflow in this specification.

  Next, as shown in FIGS. 1 and 2C, an amorphous silicon film 4 is formed on the seed layer 3.

  In this example, the base 2 is heated, a silane-based gas not containing an amino group is supplied to the seed layer 3 on the surface of the heated base 2, and the silane-based gas not containing an amino group is thermally decomposed, thereby producing a seed. An amorphous silicon film 4 is formed on the layer 3 (step 2).

Examples of silane gases that do not contain amino groups include:
SiH ₂
SiH ₄
SiH ₆
Si ₂ H ₄
Si ₂ H ₆
A silicon hydride represented by the formula Si _m H _{2m + 2} (where m is a natural number of 3 or more), and
Si hydride represented by the formula Si _n H _2n (where n is a natural number of 3 or more)
Examples thereof include a gas containing at least one of the following. In this example, SiH ₄ (monosilane) was used.

An example of the processing conditions in Step 2 is
SiH ₄ flow rate: 500 sccm
Deposition time: 30min / 45min / 60min
Processing temperature: 500 ℃
Processing pressure: 53.2 Pa (0.4 Torr)
It is.

  As described above, according to the method for forming an amorphous silicon film according to the embodiment, after the aminosilane-based gas is preflowed on the surface of the base 2, the amorphous silicon film 4 is formed on the seed layer 3.

3 and 4 show the relationship between the deposition time and the film thickness of the amorphous silicon film 4. 3 shows a case where the base 2 is a silicon oxide film (SiO ₂ ), and FIG. 4 shows a case where the base 2 is a silicon nitride film (SiN). The film thickness of the amorphous silicon film 4 was measured at three points when the deposition time was 30 min, 45 min, and 60 min.

  Lines I and III in FIGS. 3 and 4 show the results with preflow, and lines II and IV show the results without preflow. Lines I to IV are straight lines obtained by linearly approximating the three measured film thicknesses by the least square method, and the equations are as follows.

Line I: y = 17.572x-20.855 (1)
Line II: y = 17.605x-34.929 (2)
Line III: y = 18.011x-27.739 (3)
Line IV: y = 18.091x-41.277 (4)
As shown in FIG. 3 and FIG. 4, it has been clarified that the film thickness of the amorphous silicon film 4 is increased when the preflow is performed as compared with the case where the preflow is not performed.

  FIGS. 5 and 6 show the intersections of the lines I to IV and the deposition time when the above equations (1) to (4) are set to y = 0, that is, the film thickness of the amorphous silicon film is “0”. Show. 5 corresponds to an enlarged view in which a broken line frame A in FIG. 3 is enlarged, and FIG. 6 corresponds to an enlarged view in which a broken line frame B in FIG. 4 is enlarged.

  As shown in FIG. 5, when the base 2 is a silicon oxide film with a preflow, the deposition of the amorphous silicon film 4 starts from about 1.2 min (x≈1.189) from the start of the processing, whereas there is no preflow. In the case of the silicon oxide film, the deposition of the amorphous silicon film 4 starts from about 2.0 min (x≈1.984) from the start of the process.

  Further, as shown in FIG. 6, when the base 2 is a silicon nitride film with preflow, the deposition of the amorphous silicon film 4 starts from about 1.5 min (x≈1.540) from the start of the process, whereas In the case of a silicon nitride film without preflow, the deposition of the amorphous silicon film 4 starts from about 2.3 min (x≈2.282) from the start of processing.

  Thus, by performing the pre-flow of aminosilane-based gas on the base 2, the incubation time is reduced from about 2.0 min to about 1.2 min when the base 2 is a silicon oxide film, and the base 2 is a silicon nitride film. In the case of, it was possible to shorten from about 2.3 min to about 1.5 min.

  7A to 8B show observation results of the surface of the amorphous silicon film with a scanning electron microscope (SEM). 7A and 7B are secondary electron images of the surface and cross section of the amorphous silicon film having a thickness of 50 nm, and FIGS. 8A and 8B are secondary electron images of the surface and cross section of the amorphous silicon film having a thickness of 100 nm. The SEM acceleration voltage is 5.0 kV, and the magnification is 100000 times (× 100 k). The base is a silicon oxide film.

  As shown in FIG. 7A, it is clear from visual observation that the surface of the amorphous silicon film is smoother and the surface roughness is improved when the pre-flow of the aminosilane-based gas is performed as compared with the case without preflow (FIG. 7B). It was.

  Further, as shown in FIG. 8A, the same applies to an amorphous silicon film having a film thickness of about 100 nm, and the surface roughness of the amorphous silicon film is improved as compared with the case without preflow (FIG. 8B).

  As described above, according to the amorphous silicon film forming method according to the embodiment, it was found that the surface roughness was improved in the surface visual observation by the SEM.

  FIG. 9 shows an average surface roughness (surface roughness) Ra of the amorphous silicon film surface measured using an atomic force microscope (AFM). In the results shown in FIG. 9, the AFM scan size was set to 1 μm and the scan rate was set to 1.993 Hz.

  As shown in FIG. 9, when the aminosilane-based gas is preflowed, the average surface roughness (surface roughness) Ra is 0.101 to 0 in the range of the film thickness of 50 nm or more and 100 nm or less as compared with the case of no preflow. It was found to be improved by 157 nm. From the measurement result by this AFM, the film formation method of the amorphous silicon film according to one embodiment has an average surface roughness (surface roughness) Ra as compared with the case of no preflow particularly when the film thickness of the amorphous silicon film is thin. It was found that the improvement effect was high. For example, in an amorphous silicon film having a film thickness of about 50 nm, Ra = 0.411 when there was no preflow, whereas Ra = 0.254 when Ra was preflowed, and Ra was improved by 0.157 nm. Has been. This result indicates that the amorphous silicon film forming method according to the embodiment is more effective as the semiconductor device is further miniaturized.

  FIG. 10 shows the haze of the amorphous silicon film surface measured using a surface inspection apparatus. The haze shown in FIG. 10 is a haze in the DWO mode (Dark Field Wide Oblique).

  As shown in FIG. 10, it was found that the haze was improved by about 2.1 ppm in the range of the film thickness from 50 nm to 100 nm when the aminosilane-based gas was preflowed compared to the case without preflow.

  As described above, from the observation using the scanning electron microscope, the atomic force microscope, and the surface inspection apparatus, and the measurement result, the film formation method of the amorphous silicon film according to the embodiment uses the aminosilane-based gas. After the surface is pre-flowed and the seed layer 3 is formed on the surface of the base 2, a silane-based gas not containing an amino group is supplied onto the seed layer 3 and thermally decomposed, so that the accuracy of the surface roughness is high. An amorphous silicon film 4 having a small surface roughness can be formed.

  As shown in FIG. 11, such an amorphous silicon film is embedded in the contact hole 5 formed in the base layer 2, for example, an interlayer insulating film including a silicon oxide film or a silicon nitride film, or formed in the interlayer insulating film. It is useful for embedding a line formed, for example, a groove for internal wiring. 12A and 12B are enlarged views of the contact portion 6 between the surfaces of the amorphous silicon film 4 in the contact hole 5. 12A and 12B correspond to enlarged views in a broken-line circle C in FIG.

  When the surface roughness of the amorphous silicon film 4 is large, a large void 7 is generated in the contact portion 6 as shown in FIG. 12A, whereas the film is formed by using the film forming method according to the embodiment. According to the amorphous silicon film 4 having a small surface roughness, the void 7 generated in the contact portion 6 is small as shown in FIG. 12B. If the void 7 is reduced, an increase in the resistance value of the amorphous silicon film 4 embedded in the contact hole 5 can be suppressed.

  In addition, according to the continuous film formation method using the amorphous silicon with the seed layer using the disilane gas and the subsequent silane gas, which has better surface roughness than before, first, the increase in film formation at the upper corner portion of the contact hole Coverage deterioration (occurrence of voids) occurs, making it difficult to apply to fine contact holes.

  On the other hand, according to one embodiment, the coverage of film formation is improved and the surface roughness can be further improved as compared with the above-described continuous film formation method.

  Therefore, according to one embodiment, there is provided a method for forming an amorphous silicon film that can further improve the accuracy of the surface roughness of the amorphous silicon film 4 and can cope with the progress of miniaturization of contact holes and lines inside the semiconductor device. can do. The amorphous silicon film 4 formed by using the film forming method according to the embodiment is useful for embedding contact holes 5 and lines formed in the interlayer insulating film.

  Next, an example of a film forming apparatus capable of carrying out the amorphous silicon film forming method according to the embodiment will be described.

  FIG. 13 is a cross-sectional view schematically showing an example of a film forming apparatus capable of performing the amorphous silicon film forming method according to the embodiment.

  As shown in FIG. 13, 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. As a result, the object to be processed, for example, a semiconductor substrate, in this example, for example, the silicon substrate 1 on which the SiO ₂ film is deposited as a base 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.

  The processing gas supply mechanism 114 includes an aminosilane-based gas supply source 117 and a silane-based gas supply source 118 that does not include an amino group.

  The aminosilane-based gas supply source 117 is connected to the dispersion nozzle 123 via the flow rate controller 121a and the on-off valve 122a. The dispersion nozzle 123 is made of a quartz tube, penetrates the side wall of the manifold 103 inward, is bent upward, and extends vertically. A plurality of gas discharge holes 124 are formed at a predetermined interval in a vertical portion of the dispersion nozzle 123. The aminosilane-based gas is discharged substantially uniformly from the gas discharge holes 124 toward the processing chamber 101 in the horizontal direction.

  The silane-based gas supply source 118 that does not contain an amino group is connected to the dispersion nozzle 125 via a flow rate controller 121b and an on-off valve 122b. The dispersion nozzle 125 is made of a quartz tube, penetrates the side wall of the manifold 103 inward, is bent upward, and extends vertically. A plurality of gas discharge holes 126 are formed at a predetermined interval in a vertical portion of the dispersion nozzle 125. A silane-based gas not containing an amino group is discharged substantially uniformly from the gas discharge holes 126 toward 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 123 and 125. 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 a target object accommodated in the processing chamber 101, for example, a semiconductor substrate, 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 keyboard for an operator to input 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, processing according to the film forming method according to the above-described embodiment is sequentially performed.

  The film forming method according to the one embodiment can be performed by a film forming apparatus 100 as shown in FIG. Of course, the film forming apparatus is not limited to the batch type as shown in FIG. 13, but may be a single wafer type film forming apparatus.

  As mentioned above, although this invention was demonstrated according to some embodiment, this invention is not limited to the said some embodiment, A various deformation | transformation is possible.

  For example, in the one embodiment, the processing conditions are specifically exemplified, but the processing conditions are not limited to the specific examples.

  The improvement of the surface roughness of the amorphous silicon film, which is an advantage of the present invention, is that the surface of the underlayer 2 is preflowed using an aminosilane-based gas and the seed layer 3 is formed on the surface of the underlayer 2 and then the silane-based material containing no amino group. It is obtained by providing a configuration in which an amorphous silicon film 4 is formed by supplying gas onto the seed layer 3 and thermally decomposing it.

  Accordingly, the processing conditions are not limited to the specific examples described in the above embodiment, and can be changed within a range not impairing the above advantages according to the size of the silicon substrate 1, the change in the volume of the processing chamber, and the like. Of course.

Further, the film forming method described in the above embodiment can improve the surface roughness, for example, the average surface roughness Ra on the order of 0.1 nm, and thus is suitable for the manufacturing process of the semiconductor device.
Further, if the seed layer 3 is thickened, the thickness of the amorphous silicon film 4 is increased and the miniaturization of the semiconductor device is impaired. The seed layer 3 is for uniformly generating nuclei of amorphous silicon. For this reason, it is desirable that the thickness of the seed layer 3 is small, and it is preferable that the thickness is about the monoatomic layer level. If a specific thickness of the seed layer 3 is mentioned, it is preferable that the thickness be 0.1 nm or more and 0.3 nm or less.

The aminosilane-based gas is preferably a monovalent aminosilane-based gas, for example, DIPAS (diisopropylaminosilane).
Furthermore, it is preferable that the aminosilane is adsorbed on the base 2 without being decomposed. For example, DIPAS thermally decomposes at 450 ° C. or higher. When aminosilane is thermally decomposed, impurities such as carbon (C) and nitrogen (N) may be involved in the film to be formed. For example, by allowing aminosilane to be adsorbed on the base 2 without being decomposed, it is possible to obtain an advantage that the situation in which impurities are involved in the film to be formed can be suppressed.

  In addition, the thickness of the amorphous silicon film 4 is preferably 50 nm or more and 100 nm or less from the disclosure of the above-described embodiment, but may be a thickness in the range of 50 nm or less and 100 nm or more, for example.

In the one embodiment, as the silane-based gas not containing an amino group,
Si hydride represented by the formula Si _m H _{2m + 2} (where m is a natural number of 3 or more) and hydride of silicon represented by the formula Si _n H _2n (where n is a natural number of 3 or more) The so-called higher order silane was exemplified.

As the higher order silane, for example, a hydride of silicon represented by a formula of Si _m H _{2m + 2} (where m is a natural number of 3 or more),
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 )
It is good to be selected from at least one of the following.

Further, for example, a hydride of silicon represented by a formula of Si _n H _2n (where n is a natural number of 3 or more)
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 )
It is good to be selected from at least one of the following.

Furthermore, when considering a combination of an aminosilane-based gas and a silane-based gas (silicon source) that does not contain an amino group, monosilane (SiH4), disilane ( Si2H6) is preferable.
In addition, the present invention can be variously modified without departing from the gist thereof.

  DESCRIPTION OF SYMBOLS 1 ... Silicon substrate, 2 ... Base | substrate, 3 ... Seed layer, 4 ... Amorphous silicon film.

Claims (14)

Accommodating the substrate in the processing chamber;
Heating the substrate in the processing chamber;
Exhausting the processing chamber and adjusting the pressure;
Supplying an aminosilane-based gas into the processing chamber under conditions where the aminosilane-based gas is not thermally decomposed to adsorb the aminosilane-based gas to form a seed layer on the substrate;
Forming an amorphous silicon film on the seed layer by supplying a silane-based gas not containing an amino group into the processing chamber under conditions in which a silane-based gas not containing an amino group is thermally decomposed;
A method for forming an amorphous silicon film, wherein the step of forming the seed layer and the step of forming the amorphous silicon film are continuously performed in the processing chamber.   The method for forming an amorphous silicon film according to claim 1, wherein the temperature at which the aminosilane-based gas is not thermally decomposed is lower than 450 ° C. The aminosilane-based gas is
BAS (Butylaminosilane)
BTBAS (Bicter Shabutyl Butyl Silane)
DMAS (dimethylaminosilane)
BDMAS (Bisdimethylaminosilane)
TDMAS (Trisdimethylaminosilane)
DEAS (diethylaminosilane)
BDEAS (Bisdiethylaminosilane)
DPAS (dipropylaminosilane) and DIPAS (diisopropylaminosilane)
Selected from gases containing at least one of
The silane-based gas containing no amino group is
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 )
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 )
The method for forming an amorphous silicon film according to claim 1, wherein the amorphous silicon film is selected from at least one of the following. The aminosilane-based gas is DIPAS (diisopropylaminosilane),
The method for forming an amorphous silicon film according to claim 3, wherein the silane-based gas containing no amino group is selected from any one of monosilane (SiH ₄ ) and disilane (Si ₂ H ₆ ).   The method of forming an amorphous silicon film according to claim 1, wherein the seed layer has a thickness of a monoatomic layer.   6. The method for forming an amorphous silicon film according to claim 5, wherein the seed layer has a thickness of 0.1 nm to 0.3 nm.   3. The method for forming an amorphous silicon film according to claim 1, wherein an underlayer of a silicon oxide film or a silicon nitride film is formed on the surface of the substrate. A processing chamber for containing and processing substrates;
Heating means for heating the substrate housed in the processing chamber;
An aminosilane-based gas supply means for supplying an aminosilane-based gas into the processing chamber;
A silane-based gas supply means not containing an amino group for supplying a silane-based gas not containing an amino group in the processing chamber;
Exhaust means for exhausting the processing chamber;
A controller for controlling the heating means, the aminosilane-based gas supply means, the silane-based gas supply means not containing the amino group, and the exhaust means,
The controller is
Heating the substrate to a temperature at which the aminosilane-based gas is not thermally decomposed, and supplying the aminosilane-based gas into the processing chamber to adsorb the aminosilane-based gas to form a seed layer;
Supplying the silane-based gas not containing the amino group into the processing chamber to thermally decompose the silane-based gas not containing the amino group to form an amorphous silicon film;
The heating unit, the aminosilane-based gas supply unit, the step of forming the seed layer, and the step of forming the amorphous silicon layer following the step of forming the seed layer are continuously performed in the same processing chamber. A device for forming an amorphous silicon film, characterized by controlling a silane-based gas supply means not containing an amino group and the exhaust means.   The amorphous silicon film forming apparatus according to claim 8, wherein the temperature at which the aminosilane-based gas is not thermally decomposed is lower than 450 ° C. The aminosilane-based gas is
BAS (Butylaminosilane)
BTBAS (Bicter Shabutyl Butyl Silane)
DMAS (dimethylaminosilane)
BDMAS (Bisdimethylaminosilane)
TDMAS (Trisdimethylaminosilane)
DEAS (diethylaminosilane)
BDEAS (Bisdiethylaminosilane)
DPAS (dipropylaminosilane) and DIPAS (diisopropylaminosilane)
Selected from gases containing at least one of
The silane-based gas containing no amino group is
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 )
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 )
10. The amorphous silicon film forming apparatus according to claim 8, wherein the amorphous silicon film forming apparatus is selected from at least one of the following. The aminosilane-based gas is DIPAS (diisopropylaminosilane),
11. The amorphous silicon film forming apparatus according to claim 10, wherein the silane-based gas containing no amino group is selected from any one of monosilane (SiH ₄ ) and disilane (Si ₂ H ₆ ). .   The amorphous silicon film forming apparatus according to claim 8, wherein the seed layer has a thickness of a monoatomic layer.   The amorphous silicon film forming apparatus according to claim 12, wherein the seed layer has a thickness of 0.1 nm to 0.3 nm. 10. The amorphous silicon film forming apparatus according to claim 8, wherein a base layer of a silicon oxide film or a silicon nitride film is formed on the surface of the substrate.