JP3067180B2 - Method and apparatus for forming single crystal silicon film - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used, for example, for manufacturing a three-dimensional integrated circuit device, and is a single-crystal silicon film for forming a single-crystal silicon film on a surface of a substrate. The present invention relates to a forming method and an apparatus therefor.

[Background technology]

In order to realize a three-dimensional integrated circuit element in which elements such as transistors are three-dimensionally integrated on a substrate, a semiconductor crystal of sufficient quality for forming the element is formed on an amorphous insulator. Technology is required.

As a conventional technique for forming a silicon film on an insulator,
Some use laser annealing. This is a technology in which a thin amorphous silicon film or polycrystalline silicon film of 1 μm or less is formed on an insulating film, and this is irradiated with a powerful laser beam. This is to utilize the phenomenon of single crystallization when solidifying again.

However, this prior art is still in the research stage at present, and has not been established to the point where three-dimensional integrated circuit elements can be manufactured. That is, in crystal growth by laser recrystallization, a crystal defect is likely to occur under the influence of a change in laser output, a pattern defect of a sample, a change in a beam system, and the like, which is sufficient for forming an element such as a semiconductor element. A high quality semiconductor single crystal cannot be formed.

As a solution to such a problem, a single-crystal silicon film formation method capable of forming a high-quality single-crystal silicon film on the surface of a substrate regardless of the properties of the surface has been previously proposed by the same applicant. (Japanese Patent Application No. 1-91271
issue). The summary is as follows.

That is, when silicon is deposited on the surface of the insulator, crystal grains oriented in various directions grow to form a silicon film (polycrystal). When the silicon film is irradiated with ions, silicon atoms are sputtered by the ions. Be affected. The amount of silicon atoms sputtered at this time is proportional to the number of collisions between ions and silicon atoms.

However, when the crystal axis has a low index in a crystal grain having a crystal axis along the direction of incidence of ions, when the crystal grain is viewed from the ion, the crystal grain is represented by "S" shown by the symbol A in FIG. Looks like an open structure. When ions enter the "su", the ions are less likely to collide with silicon atoms and pass through the "su" channel. Therefore, when ions enter the crystal grains from a direction along the low-index crystal axis, the number of collisions between the ions and silicon atoms is small, and the sputtering rate is reduced. That is, it can be said that the sputtering rate of silicon atoms in each crystal grain having a different crystal axis along the ion incident direction is determined by the crystal axis of each crystal grain.

Furthermore, according to Onderdelinden's hypothesis, the crystal axis <uvw>
The sputtering rate Y <uvw> due to the incidence of ions from the direction along this crystal axis has the following relationship with the interatomic distance t _uvw :

Y <uvw> ∝t _uvw ^{3/2 When} this equation is applied to a silicon crystal, each crystal axis <11
The following relationship is established for <0>, <111>, and <100>.

Further, considering the higher-order exponent axis, the following relationship is established: Y <110><Y<111><Y<100><Y<higher-orderindex>.

The display <110> collectively shows [110] and directions equivalent thereto (the same applies to other cases).

Therefore, when ions are irradiated on a silicon film having crystal grains oriented in various directions, more crystal grains having a crystal axis <110> remain along the ion irradiation direction.

Therefore, silicon is deposited on the surface of the insulator by a method such as vapor deposition, and the surface of the insulator is irradiated with ions to form a silicon crystal with the crystal axis <110> oriented in the direction of incidence of the ions. Is possible. However, even if the direction of the crystal axis <110> is determined in this way, if the direction of the crystal axis <100> or <111> is not determined, the formed silicon film cannot be a single crystal film.

To explain this in detail, FIG. 4 shows that the silicon crystal [011]
It is a stereo projection figure centering on an axis. As can be seen from this figure, in the silicon crystal, the angle between the crystal axes <110> is 60 ° or 90 °, and the crystal axes <110> and <10>
0> is 45 ° or 90 °, and the angle between the crystal axes <110> and <111> is 35.3 ° or 90 °. Therefore, for example, when the ions 4 are irradiated perpendicularly to the substrate 2 as shown in FIG. 5, the crystal axis <110> is oriented in the incident direction of the ions. 6, the crystal axis <111> can be taken in any direction within the side of the cone having a generating line at an angle of 45 ° with respect to the direction perpendicular to the substrate 2 as shown in FIG. Any direction could be taken within the side of the cone with the generating line at an angle of 35.3 °. Thus, a single crystal film cannot be formed only by irradiating the substrate 2 on which silicon is deposited with ions from one direction.

The prior application solved this point. That is, by irradiating ions from at least two directions and selecting the angle formed by the irradiation directions of the ions equal to the angle between the crystal axes <110>, the crystal axis < The direction of the crystal axis other than <110> can be defined as a fixed direction. Then, at this time, the incident angle of ions with respect to the substrate on which the single crystal silicon film is to be formed is
If you choose equal to the angle between the crystal axes <110> and <100>,
A silicon crystal with a crystal axis <100> oriented in a direction perpendicular to the substrate can be grown. If the incident angle is selected to be equal to the angle between the crystal axes <110> and <111>, a silicon crystal having the crystal axis <111> oriented in a direction perpendicular to the substrate can be grown.

Apparatus configurations for this are shown in FIGS. 7 and 8. In this example, an electron beam heating type evaporation source 8 is disposed for depositing silicon toward the substrate 2 having a temperature of about room temperature to about 700 ° C., and two ion sources 6 and 7 are disposed for sputtering. Have been. The direction of irradiation of the substrate 2 with ions (eg, inert gas ions such as argon) 4 from the ion sources 6 and 7
R1 and R2 both form an angle α with respect to the substrate 2, and the orthogonal projection of the irradiation directions R1 and R2 onto the surface of the substrate 2 forms an angle β. In the example of FIG. 7, α ≒ 45 ≒ and β ≒ 180 ゜ are set (however, β ≒ 90 ゜ may be used). In this way, as shown in FIG. 9, a crystal axis <100> is formed in a direction perpendicular to the substrate 2 and a crystal axis <110> forming an angle of 45 ° with the crystal axis is formed in the same plane. An arrayed silicon crystal can be obtained. In this case, both crystal axes <110>
Form a 90 ° angle with each other.

In the example shown in FIG. 8, α54.7 and β120 are set. In this manner, as shown in FIG. 10, the crystal axis <111> is perpendicular to the substrate 2.
And a silicon crystal in which crystal axes <110> forming an angle of 35.3 ° with this are arranged in the same plane.
In this case, both crystal axes <110> form an angle of 60 ° with each other.

According to the above-described means, a silicon crystal having a uniform crystal axis <110> and <100> or <111> can be grown on the surface of the substrate 2. A high quality single crystal silicon film is formed.

[Object of the invention]

However, in the above prior art example, although a single crystal silicon film can be formed, its productivity (throughput) is not particularly considered.

That is, if the deposition of silicon on the substrate 2 and the irradiation of ions as described above are performed in one processing chamber, not only the two ion sources 6 and 7 but also the evaporation source 8 are three-dimensionally provided. Since they must be arranged, the processing chamber becomes very large. As a result, the evacuation time accompanying the loading / unloading of the substrate 2 becomes longer, and all the processing must be stopped when the substrate 2 is loaded / unloaded, so that a loss time occurs.
It is difficult to increase throughput.

Accordingly, the present invention mainly aims to provide a method and an apparatus for forming a single crystal silicon film capable of further improving such a point and increasing the throughput and thereby reducing the film formation cost. Aim.

[Summary of the Invention]

In order to achieve the above object, a method of forming a single crystal silicon film according to the present invention is, in a simple manner, directed to a first step of depositing silicon on a surface of a substrate, and a method of forming a silicon layer on the surface of the substrate after the first step. The method is characterized by comprising a second step of irradiating ions from at least two predetermined directions as described above, and a third step of depositing silicon on the surface of the substrate after the second step.

Further, in brief, the single crystal silicon film forming apparatus of the present invention comprises a first processing chamber provided with means for depositing silicon on a surface of a substrate, and a substrate transferred from the first processing chamber. A second processing chamber provided with means for irradiating ions to the surface of the substrate from at least two predetermined directions as described above, and depositing silicon on the surface of the substrate transferred from the second processing chamber. Third provided means
And a substrate transfer means for transferring the substrate from the first processing chamber to the third processing chamber via the second processing chamber.

〔Example〕

FIG. 1 is a schematic diagram showing an example of a single crystal silicon film forming apparatus according to the present invention. FIG. 2 is a line I- of FIG.
It is a schematic sectional drawing which follows I. The same reference numerals are given to the same or corresponding portions as those in the above-described prior example, and differences from the preceding example will be mainly described below.

In this apparatus, the first step of depositing silicon on the surface of the substrate 2 is performed in the first processing chamber 10 from at least two predetermined directions as described above toward the surface of the substrate 2 that has undergone the first step. The second step of irradiating ions is performed in the second processing chamber 20 adjacent to the processing chamber 10, and the third step of further depositing silicon on the surface of the substrate 2 after the second step is performed in the processing chamber 20. The processing is performed in the third processing chamber 30 adjacent to the processing chamber.

A vacuum valve 41 is provided between the processing chambers 10, 20, and 30 and before and after the processing chambers.
To 44 are provided.

Further, between the processing chambers 10, 20, and 30, although not shown, the substrate 2 is transferred from the processing chamber 10 through the processing chamber 20 to the processing chamber 30.
More specifically, the substrate 2 is transported to the electrode 11 also serving as a holder described below in the processing chamber 10, and the substrate 2 having been processed there is transported to the holder 21 described below in the processing chamber 20. Then, there is provided a substrate transfer means for transferring the processed substrate 2 to an electrode 31 also serving as a holder in the processing chamber 30 which will be described later, and further transferring the processed substrate 2 out of the processing chamber 30 there. ing. Arrow B in the figure indicates the transport direction. This substrate transfer means is specifically configured using a transfer belt, a transfer arm, and the like.

In the processing chamber 10, two parallel plate-like electrodes 11 and 12 to which high-frequency power is supplied from an external high-frequency power supply 14 are provided. These also serve as holders, and one electrode
The substrate 2 as described above is mounted on 11. The other electrode
12 holds a silicon target 13 for sputtering.

Accordingly, the substrate 2 is mounted on the electrode 11, the inside of the processing chamber 10 is evacuated, and a sputtering gas such as argon is introduced into the processing chamber 10 at a predetermined pressure (for example, about 10 ^-2 to 10 ^-3 Torr). When high-frequency power is supplied between the two electrodes 11 and 12, a high-frequency discharge is generated between the two electrodes 11 and 12, and plasma is generated.
Thereby, the silicon target 13 is sputtered, and silicon is deposited on the surface of the substrate 2. Thereby, the substrate 2
Formed on the surface is a polycrystalline silicon film. The film thickness is, for example, about several tens nm.

In the processing chamber 20, a holder 21 for holding the substrate 2 is provided. Inside or behind the holder 21, a heating source 22 for heating the substrate 2 is provided as necessary, for example, as shown in FIG.

In this embodiment, two ion sources 6 and 7 as described above are provided on the side wall of the processing chamber 20 in a predetermined arrangement as described with reference to FIG. 7 or FIG. I have.

That is, when obtaining a silicon crystal with the crystal axis <100> oriented in a direction perpendicular to the substrate 2, the angle α between the surface of the substrate 2 and the irradiation direction of the ions 4 is set to approximately 45 °, and The angle β (not shown in FIG. 2) formed by the orthogonal projection of the irradiation direction to the surface of the substrate 2 is approximately 180 ° or approximately 90 °.
さ れ るWhen obtaining a silicon crystal in which the crystal axis <111> is oriented in a direction perpendicular to the substrate 2, the above α is approximately 5
It is made 4.7 ° and β is made almost 120 °.

Therefore, the substrate 2 having silicon deposited on the surface in the previous step is mounted on the holder 21 and the inside of the processing chamber 20 is evacuated to a predetermined degree of vacuum (for example, about 10 ^-5 to 10 ^-6 Torr). And
Irradiation with ions (eg, inert gas ions such as argon) 4 from both ion sources 6 and 7 causes the crystal axis <100> or <11> by the above-described sputtering action.
Only the crystal grains with <1> oriented perpendicular to the surface of the substrate 2 can be left. That is, nucleation of single crystal silicon can be performed on the surface of the substrate 2.

In the processing chamber 30, two parallel plate-shaped electrodes 31 and 32 to which high-frequency power is supplied from an external high-frequency power supply 34 are provided. These also serve as holders, and one electrode
The substrate 2 is mounted on 31. On the other electrode 32, a silicon target 33 for sputtering is held.

Therefore, the substrate 2 having a nucleus formed on the surface in the previous step is mounted on the electrode 31 and the inside of the processing chamber 30 is evacuated and a sputtering gas such as argon is applied thereto at a predetermined pressure (for example,
10 ^-2 to 10 ^-3 Torr).
When high-frequency power is supplied between the electrodes 32, a high-frequency discharge is generated between the electrodes 31 and 32 to generate plasma, whereby the silicon target 33 is sputtered and silicon is deposited on the surface of the substrate 2.

In this case, since nucleation of single crystal silicon has been formed on the surface of the substrate 2 in the previous step, epitaxial growth is performed by depositing silicon thereon as described above, and the single crystal silicon film is formed. It is formed. Accordingly, a single crystal silicon film having a required film thickness may be obtained.

As described above, a single-crystal silicon film is formed by the steps of depositing silicon on the surface of the substrate 2, irradiating the substrate 2 with ions to form nuclei, and depositing silicon thereon to form single-crystal silicon. By performing the growth step in three steps, a large number of substrates 2 can be continuously formed into a film with a reduced loss time, so that the throughput is improved.

Further, in the above-described apparatus, in each of the processing chambers 10, 20, and 30, it is only necessary to perform a process dedicated to each process.
The size of 0, 20, and 30 can be reduced, and the evacuation time can be shortened. In addition, all the films can be processed in vacuum by forming the films in-line. As a result, the throughput can be improved. Further, it can easily cope with a large area substrate 2.

According to the present invention, a single crystal silicon film can be formed regardless of whether or not the substrate 2 has a uniform plane orientation. Therefore, the substrate 2 is not limited to a specific one. For example, a glass substrate, a silicon substrate, or the like may be used, or a substrate on which an amorphous insulating layer is formed may be used.

The means for depositing silicon on the surface of the substrate 2 before and after nucleation is not limited to sputtering as in the above example, but may be vacuum deposition, CVD (chemical vapor deposition), or the like.

The energy of the ions 4 extracted from the ion sources 6 and 7 is not limited to a specific one, but may be, for example, 100 eV to 1 eV.
It is preferably about 00 KeV (more preferably, 500 eV to 10 KeV). This is because silicon is likely to be sputtered.

Further, in the second step, that is, in the processing chamber 20, the orthogonal projection of the ion source onto the surface of the substrate 2 is substantially 90 ° or 180 ° relative to each other, as can be seen from the stereoscopic projection of FIG. May be used (when obtaining a silicon crystal with the crystal axis <100> oriented perpendicular to the substrate 2), or three may be used to form an angle of approximately 120 °. (To obtain a silicon crystal with the crystal axis <111> oriented perpendicular to the substrate 2). Alternatively, holder 21
If the substrate 2 can be rotated by rotating, the same film forming process can be performed using one fixed ion source.

〔The invention's effect〕

As described above, according to the single-crystal silicon film forming method of the present invention, the formation of the single-crystal silicon film includes the steps of: depositing a silicon film on the surface of the substrate; irradiating the surface with ions to form nuclei; Since the process is performed in three steps of depositing silicon thereon and growing single-crystal silicon, a large number of substrates can be continuously formed with reduced loss time, thereby improving throughput. I do. As a result, the film formation cost can be reduced.

Further, according to the single crystal silicon film forming apparatus of the present invention,
In each processing chamber, processing only for each process may be performed, so that each processing chamber can be reduced in size and the evacuation time thereof can be shortened. In addition, the film formation can be made inline. As a result, the throughput can be improved, and the film formation cost can be reduced. Further, it can easily cope with a large-area substrate.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an example of a single crystal silicon film forming apparatus according to the present invention. FIG. 2 is a line II of FIG.
FIG. FIG. 3 is a diagram schematically showing the structure of a silicon crystal viewed from a low-index crystal axis direction. FIG. 4 is a stereographic projection centered on the [011] axis of the silicon crystal. FIG. 5 shows the silicon crystal axis <11 when the substrate on which silicon was deposited was irradiated with ions.
It is a figure which shows the direction of <0> and <100>. FIG. 6 is a diagram showing the orientation of the crystal axes <110> and <111> of silicon when the substrate on which silicon is deposited is irradiated with ions. 7 and 8 are diagrams each showing a basic configuration for implementing a method of forming a single crystal silicon film as a background of the present invention. FIG. 9 and FIG. 10 are diagrams showing the orientation of each crystal axis of a silicon crystal formed on the surface of the substrate. 2 ... substrate, 4 ... ion, 6,7 ... ion source, 10 ...
1st processing chamber, 13 ... silicon target, 20 ... second
Processing chamber, 30... Third processing chamber, 33... Silicon target.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) H01L 21/203 C30B 29/06

Claims (4)

(57) [Claims] A first step of depositing silicon on the surface of the substrate, and an irradiation direction of ions with respect to the surface of the substrate after the first step forms an angle of 40 ° with respect to the surface of the substrate; The angle formed by the orthogonal projection of the ion irradiation direction onto the substrate
A single crystal, comprising: a second step of irradiating ions from at least two directions at 90 ° or 180 °; and a third step of depositing silicon on the surface of the substrate after the second step. Silicon film formation method. 2. A first step of depositing silicon on a surface of a substrate, and an irradiation direction of ions with respect to the surface of the substrate after the first step forms an angle of 54.7 °. A second step of irradiating ions from at least two directions in which the angle of the orthogonal projection of the ions onto the substrate is 120 °, and depositing silicon on the surface of the substrate after the second step. A method of forming a single crystal silicon film, comprising: a third step. 3. A first processing chamber provided with a means for depositing silicon on a surface of a substrate, and a first processing chamber adjacent to the first processing chamber and facing a surface of the substrate conveyed therefrom. Means for irradiating ions from at least two directions in which the surface and the direction of ion irradiation form an angle of 45 °, and the angle of orthogonal projection of the direction of ion irradiation to the substrate becomes 90 ° or 180 °. A second processing chamber provided with a second processing chamber, a third processing chamber adjacent to the second processing chamber and provided with a means for depositing silicon on a surface of the substrate conveyed from the second processing chamber; A substrate transfer means for transferring the substrate from the first processing chamber to the third processing chamber via the second processing chamber. 4. A first processing chamber provided with a means for depositing silicon on a surface of a substrate, and a first processing chamber adjacent to the first processing chamber and directed to a surface of the substrate conveyed therefrom. Means are provided for irradiating ions from at least two directions in which the surface and the direction of irradiation of ions form an angle of 54.7 °, and the angle of orthogonal projection of the direction of irradiation of ions to the substrate becomes 120 °. A second processing chamber, a third processing chamber adjacent to the second processing chamber, and provided with a means for depositing silicon on the surface of the substrate conveyed therefrom; A single-crystal silicon film forming apparatus, comprising: a substrate transfer means for transferring the first processing chamber to the third processing chamber via the second processing chamber.