JP3128586B2 - Thin film growth equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for growing a thin film on a substrate made of silicon, glass or the like, and to a thin film growth apparatus for obtaining a high concentration distribution (specific resistance distribution, etc.).

[0002]

2. Description of the Related Art Conventionally, as a concentration control method in a thin film growth apparatus such as a thermal CVD,

(1) A method in which a source gas such as a reaction gas or a dopant gas (hereinafter referred to as a dopant gas) is controlled by one flow controller (hereinafter referred to as an MFC (mass flow controller)). (2) A method in which the dopant gas is controlled by two MFCs. (3) A method in which the dopant gas is controlled by three MFCs. There is. Hereinafter, these methods will be described with reference to FIGS.
This will be described with reference to FIG. 11 to 13 are system diagrams for controlling a conventional dopant gas.

FIG. 11 is a system diagram showing a first example for obtaining a concentration distribution conventionally performed. An on-off valve PV5 is provided in a pipeline PL1A extending upward from the cylinder 23 containing DN (dopant N gas), and communicates with the flow controller MFC3. Here, the designated flow rate flows on the pipeline PL1A. If it is necessary to discharge to the vent (VENT) line due to the sequence configuration, open / close valve P
It is discharged to the vent line PL6A through V10.

[0005] In the case of the system shown in FIG.
From the viewpoint of reproducibility, it is high because it is controlled by one MFC. However, the maximum flow rate of MFC
Since the range of about 5% cannot be controlled, a large capacity MF
When C is used, control on the small flow rate side becomes impossible, but in order to obtain a high concentration distribution, gas cylinders having different concentrations must be replaced. That is, since the concentration is uniquely determined by the flow rate range of the MFC 3, it is necessary to exchange the MFC 3 or the cylinder 23 having a different concentration in order to obtain a wide concentration distribution. At the same time,
It is no longer compatible with the current situation of high-mix low-volume production.

FIG. 12 is a system diagram showing a system in which the disadvantage of the system of FIG. 11, that is, a point where the density range is narrow can be removed. MFC3 and on-off valve PV11A, MF
What connected the C4 and the on-off valve PV11B in series, respectively, is the on-off valve PV10 and the valve PV5 of the pipeline PL1A of FIG.
Are connected in parallel between the MFC3 and the MFC4 after determining whether to use the MFC3 or the MFC4 based on different setting (command) flow values of the two flow ranges.
This is to excite one of the valve 1A and the valve PV11B.

In the method shown in FIG. 12, it is necessary to determine which of MFC3 and MFC4 is to be used, based on a set (command) flow value having a different flow range. In this case, the complexity and supply gas concentration are univocal. Different M
Even if FC is prepared, the obtained concentration distribution is necessarily limited, so that a wide range of concentration distribution cannot be obtained.

FIG. 13 is a system diagram of an autodopant control (ADC) system which is a third example conventionally performed. Pipe line PL extending upward from cylinder 23
1A is provided with an on-off valve PV5, which communicates with a flow controller MFC5 called a source. The dopant gas set to a constant concentration coming out of the MFC 5 passes through the mixer MX and is mixed with a carrier gas (here, H ₂ gas) supplied from the lower opening / closing valve PV11 to be mixed with the MFC 3 on the injection side and the vent line side. Connected to MFC4.

Here, the method of FIG. 13 has an advantage that a relatively wide range of density distribution can be obtained as compared with the method of FIG. That is, if the dopant gas flow rate is determined by the MFC 5, the flow rates of the MFC 3 and the MFC 4 are automatically determined accordingly, and thereby the concentration is determined.
According to the method, a dopant gas having a constant concentration flowing out of the MFC 5 is mixed with a carrier gas (hydrogen or the like) in a mixer MX, and a part of the mixed gas is injected (injected) into a reaction part, and dilution is performed. The (diluted) excess gas is discharged to the vent line PL6A. At this time, the concentration of the mixed gas is MFC3 and MFC4.
Is determined by the flow ratio.

The relational expression between the set flow rates of the MFC 3 and the MFC 4 is such that when the ratio of the set flow rate of the MFC 3 to the maximum flow rate of the MFC 3 is x, the set flow rate of the MFC 4 is 1-x with respect to the maximum flow rate. For example, the maximum flow rate of the MFC 3 on the injection side is 300 cc / min,
Maximum flow rate of MFC4 on vent line side is 30L / min
, Set the injection flow rate to 100cc
/ Min, the flow rate on the vent line side is 1
This is a control method of 20 L / min from -x. Normal M
Since the flow rate of FC3 is set equal to that of MFC5, the dopant gas from the cylinder 23 is diluted to a ratio of x / (1-x) and supplied to the reaction unit via MFC3. Here, the on-off valve PV10 and the valve PV11 are excited when the sequence to be mixed is executed, and when the sequence for supplying to the reaction furnace R1 is reached, the on-off valve PV10 is closed.

The method shown in FIG.
Although it has the drawback of increasing the number of FC5 components, it is used in that a relatively wide concentration distribution can be obtained. At present, however, there is an increasing demand for a further wide concentration distribution. Was.

[0012]

By the way, a thin film growth apparatus is required to make the thickness, specific resistance, sheet resistance, etc. of a grown film obtained by the thin film growth apparatus uniform, and to provide a product corresponding to high-mix low-volume production. It is required to be manufactured. In order to improve productivity and yield, it is necessary to minimize downtime such as maintenance time and failure time on the apparatus. In particular, when product varieties vary widely,
If the gas cylinder needs to be replaced for each product type, it will be a major obstacle to productivity and will have a great effect on the product price. In addition, there is a demand for a device that can manufacture a product having a specific resistance value or a concentration distribution from a low resistance to a high resistance even in a variety.

In view of the above, the present invention provides a thin film growth apparatus in which a gas having a required concentration is guided to a reaction furnace, and a product having a wide range of concentration distribution can be obtained with a single apparatus for growing a thin film. The purpose is to:

[0014]

In order to achieve the above object, the present invention is to dispose a substrate such as silicon or glass in a reaction furnace and mix at least one kind of source gas from a gas supply source with a carrier gas. A predetermined flow rate of the raw material gas mixed and diluted to a predetermined concentration by a vessel is combined with a separately supplied carrier gas and supplied into the reaction furnace, and a thin film is formed on the substrate by vapor phase growth. A thin film growth apparatus, which is disposed between the gas supply source and the mixer, between the reaction furnace and the mixer, and between the mixer and a vent line, and capable of controlling the gas flow rate. A first flow controller for controlling the flow rate by the first flow controller and a carrier gas by the mixer in accordance with a set value of the second and third flow controllers; Source gas diluted to the desired concentration with A thin film growth apparatus which can be supplied to the reaction furnace by being combined with the carrier gas sent separately through the second flow controller, wherein the gas flow of the third flow controller leading to the vent line And the supply of the carrier gas to the mixer is configured to be capable of being cut off independently, and the first and second flow controllers are configured without diluting the source gas from the gas supply source. This is a thin film growth apparatus in which the flow rate is controlled by the above method so as to be combined with the carrier gas sent separately and supplied to the reaction furnace.

[0015]

According to the present invention, an MFC for dilution is used.
By interrupting the gas flow and giving a command signal equivalent to the flow value set in the MFC that controls the supply amount from the gas supply source, the necessary concentration of the source gas not diluted by the carrier gas is supplied to the reaction section. Be guided. This gives 1
The two devices give products with a wide range of concentration distributions.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view of a vertical type vapor phase growth apparatus, into which a high-frequency generator 11, main bodies 12 and 13 of a vapor phase growth apparatus provided with reactors R 1 and R 2, and each reactor (reaction section). A control unit 14 for controlling the gas flow rate, temperature, etc.,
An operation panel 14A including an operation key input unit and a display unit;
Control panels 12A and 13A for performing operations such as opening and closing
And a gas control device 15 having a flow controller for controlling the flow rate of various gases supplied from a factory line (including a cylinder) and an on-off valve.

FIG. 2 is a system diagram of each component of the gas control device 15. In FIG. 2, the gas supplied to the reactors R1 and R2 is N ₂ ,
H ₂ , SiCl ₄ , DN, HCl fluid cylinders 20,
21, 22, 23, 24. Cylinder 22
Constitutes a bubbling chamber, and silicon tetrachloride S
It contains a fluid such as iCl ₄ or trichlorosilane SiHCl ₃ . A pressure switch PS1 and a normally open valve PV1 (hereinafter referred to as a normally open valve) are provided in a pipeline PL1 extending upward from the cylinder 20, and communicate with a normally open valve PV7.

A pressure switch PS2 and a valve PV2 are provided in a pipeline PL2 extending upward from the cylinder 21.
Leads to 8. The outlet ports of the valves PV7 and PV8 merge and are connected to the pipelines PL1 and PL2 via the respective flow controllers MFC1 and MFC2. Pipeline PL
1 further includes gas merging valves PV23, PV19, PV
20 is provided between the reactor R1 and a pipe PL1.
A, the gas supplied from PL2A, PL3A is supplied to the valve PV
19, PV20 and PV23 can be mixed by exciting them.

Further, a gas merging valve P is provided on the line PL2.
V24, PV21 and PV22 are provided between the reaction path R2, and the gases supplied by the pipe lines PL1A, PL2A and PL3A can be mixed by exciting the valves PV21, PV22 and PV24. From the bubbling chamber 22, two lines PL3A, P3
L3B extends and is connected to valve VC. An H ₂ gas (carrier gas) enters the port PO of the valve VC via a line PL5, enters the bubbling chamber 22 via a line PL4A and a valve PV3, and receives liquid SiCl.
_{4 is} bubbling.

Accordingly, in the space inside the bubbling chamber 22, a mixed gas of vaporized SiCl ₄ and H ₂ is formed, which is connected to the valve VC through the valve PV3 on the line PL4B, and a specified amount of the mixed gas is mixed. Passes through the output port P1,
It is connected to the conduit PL3A. The control unit X is connected to the pipeline PL1A connected to the DN cylinder 23 via a valve PV5, and the DN gas discharged from the control unit X is connected to the pipeline PL1A.

A pipe P connected to the chamber 24
L2A is provided with a valve PV6A and a flow controller MFC7.
It is connected to the mixing port of V22. In addition, MFC
7 exits from the normally open valve PV2 due to the sequence configuration.
6, it is connected to an exhaust gas treatment device (not shown) via a vent line PL6A for stabilizing the flow rate and purging the line. The normally open valve PV25 connected to the pipeline PL3A also plays a role similar to the normally open valve PV26.

Here, the control unit X will be described. The piping system will be described with reference to FIGS. FIG. 3 shows a first example of the control unit X. The difference from the conventional system shown in FIG. 13 is that the valve PV12 is provided between the vent line PL6A and the MFC4.

In such a configuration, the valve PV1
By closing the valve 2 and the valve PV11, a system using only the MFC5 (source) and the MFC3 (injection) is configured. Therefore, unlike the conventional system of FIG. 13, which uses the MFC3, MFC4, and MFC5 to unconditionally dilute the carrier gas with the carrier gas, a constant concentration of dopant gas is supplied. This method is called a dilution cut method.

Instead of providing the valve PV12, the MFC
Needless to say, the structure itself can be cut off. This means that MF, like MFC5 and valve PV5,
The same applies to other MFCs provided with a pair of C and a valve.

By adopting this method, two methods of the conventional ADC method and the dilution cut method can be used.
Since it can be realized with one device, a product having a wider concentration distribution can be obtained. This is apparent from the characteristic diagram of the flow rate and the specific resistance shown in FIG. This is because the control range in the related art is P, but is expanded by Q in the present embodiment. FIG. 4 shows a second example of the control unit X. A plurality of sets of a system such as a dopant P gas (DP) similar to the system diagram of FIG.
Are connected to a conduit PL1A to connect the valves PV19 and PV shown in FIG.
21 shows an example of selectively leading to 21. Valve PV14, PV
Reference numeral 14 'denotes an on-off valve for the selection, and the valve PV10 is commonly used for each system.

FIG. 5 shows a third example of the control unit X. In the system diagram shown in FIG. 3, a throttle section T1 and a valve are provided between a carrier gas pipeline and a connection point between the mixer MX and the valve PV11. PV13 is provided. The throttle portion T1 and the valve P
The role of V13 is that when the valve PV11 is closed when the source gas is stopped, MFC3 and MFC4 are supplied to the carrier gas (H
₍₂ gases or H ₂ gas or other gases), and a relatively small flow rate of a carrier gas is passed to clean the piping and MFC and to increase the purity. By adopting this system, a product with a highly reproducible concentration can be obtained. This is because impurities remain on the line including the mixer MX. Note that the throttle portion T1 may be incorporated in the valve PV13.

Next, the control section of the control unit X will be described with reference to the block diagram of FIG. In the figure, reference numeral 50 denotes a central processing unit (hereinafter referred to as a CPU) of the main computer.
A data bus 51 and an I / O bus 52 are connected to the PU 50. The data bus 51 includes each reactor R1 or R2.
Is connected to a first storage unit 54 for storing data such as a heating temperature, a gas flow rate, and a pressure relating to a series of processes performed in.

Further, the data bus 51 has a second storage section 53 for registering fixed data composed of a ROM, a process processing program 55a for operating the present apparatus, and is controlled by the process processing program 55a. The MFCs 3, 4, and 5 and the valves PV5 and PV1 in FIGS.
Flow program 55 for controlling 0, 11, 12, 13
b (this flow program is a process processing program 5
5a) and a selection program 55 for determining whether or not to perform the dilution cut control.
c, and process information such as a sequence is corrected, edited, and registered by using a keyboard (not shown), which is one of the components of the input / output device 58, and the contents are changed by the same component. A third storage unit 55 storing another processing program 55d to be displayed on one display (not shown) or the like is connected.

The first storage unit 54 stores data used during the operation of the apparatus, such as analog / digital signal information from the keyboard, various switches and detectors, process information for actual thin film growth, and the like. This area stores information indicating whether or not to perform the dilution cut control. The I / O bus 52 has an MFC
And an input / output module 56 for driving the valve 59. The input / output module 56 includes a digital output unit (not shown) for driving each valve, an output unit (D / A converter: not shown) for giving a command signal to the MFC, and an input for taking an actual flow rate signal from the MFC. (A / D converter: not shown). The I / O bus 52 is connected to another interface module 57 connected to an input / output device 58. The input / output device 58
Is composed of the aforementioned keyboard and display, various switches, detectors, motors and the like.

FIG. 8A shows sequence (process program) information Ipp necessary for executing a process, and FIG. 8B shows the data bit code of FIG. 8A. This table has almost the same structure as that of FIG. 13 (a) of Japanese Patent Publication No. 63-28495, but this publication discloses whether to perform the dilution cut control in controlling the dopant gas. No information is included.
This information is embedded in the data bit code, but may be embedded elsewhere in the separate Ipp.

FIG. 9 is a flowchart for explaining the details of the process control (corresponding to 55a in FIG. 7). In the figure, Step 1 (hereinafter ST1-1 hereinafter) start switch of the reaction furnace R1 in FIG. 1 being pressed, moves to ST1-2, where the process program relating to R ₁ PP (i) It is checked whether or not the sequence remaining time = 0. This sequence remaining time is subtracted by the second processing program which is one of the other processing programs shown at 55d in FIG.

If the remaining time of the sequence is equal to 0 in ST1-2, the next process program PP (i) is designated in ST1-3 and its data is taken in. In ST1-4, ST1-5, ST1-6,
The sequence time, flow rate, and temperature parameters of the registered PP (i) information are set and output, and the gas valve is opened and closed. Subsequently, in ST1-7, it is checked whether or not there is information of the dilution cut control request. If there is, the flow program (55b shown in FIG. 7) is called in ST1-8.

This flow program gives an instruction to close the normally open valves PV12 and PV11 shown in FIG. 3 and to stop the flow monitoring of the MFC 4. Based on this command, a flow comparison program (not shown), which is one of the other processing programs 55d, stops sampling and flow comparison of the MFC 4.

Here, in the original control, ST1-7 and ST1-8 are set to ST1-7 due to the timing of opening and closing the gas valve.
1-5 and ST1-6,
In order to make the operation easy to understand, it is described in this way. Next, in ST1-9, i is incremented to i ← i + 1 in preparation for the next sequence set. If the start switch of R1 is OFF in ST1-1, ST1-1
0, where the start switch O of the reactor R2 is
Check N, OFF. Since the subsequent flow is the same as that of R1, the description is omitted here.

FIG. 10 is a selection program (55c in FIG. 7) for determining whether or not to perform the dilution cut control in executing the above-described process. Here, the designated information is used for the determination in ST1-7 in FIG. In the figure, in ST2-1, a sequence number for performing dilution cut control is input. In ST2-2, it is checked whether or not the input value is a sequence that can perform the dilution cut. If not, it is checked in ST2-7 whether the input value is an end request. If the request is an end request, the function ends. If not, a fault message indicating that the sequence number is incorrect is output, and a warning is issued (ST2).
-8) Capture the input again. When the target sequence number is input, a query is made in ST2-3 as to whether to perform dilution cut control in the sequence. The input is a key input of either YES or NO. When input is made in ST2-4, a check is made in ST2-5. If YES, the process proceeds to ST2-5, where the “DN (dilution cut)” flag of the data bit code shown in FIG. 8 is set to 1 and the “DN (ADC)” flag is set to 0. If NO, the process proceeds to ST2-9, where the data bit code “D
N (dilution cut) flag to 0, and
N (ADC) "flag is set to 1. Each condition is
If set, we will return to the first question for the next sequence to change.

As described above, according to the embodiment of the present invention, not only the concentration distribution obtained in the conventional apparatus but also a broader distribution can be obtained, and the downtime can be reduced and the operation of the apparatus can be reduced. The rate has improved, and the production of a wide variety of products has become possible with a single device.

It is to be noted that the present invention is not limited to the above-described embodiment, but includes low pressure chemical vapor deposition (LPCVD),
The present invention can be similarly applied to a thin film growth apparatus such as plasma chemical vapor deposition (PECVD), photochemical vapor deposition (photoCVD), and sputtering.

[0038]

According to the present invention described above, there is provided a thin film growth apparatus in which a gas having a required concentration is guided to a reaction section and a product having a wide range of concentration distribution can be obtained with one apparatus in growing a thin film. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a schematic configuration of a vertical thin film growth apparatus according to the present invention.

FIG. 2 is a block diagram showing an example of the gas control device of FIG.

FIG. 3 is a piping system diagram showing a first example for controlling the gas of FIG. 1;

FIG. 4 is a piping diagram showing a second example for controlling the gas of FIG. 1;

FIG. 5 is a piping diagram showing a third example for controlling the gas of FIG. 1;

FIG. 6 is a characteristic diagram of the flow rate and the specific resistance of FIG.

FIG. 7 is a block diagram of the control unit in FIG. 2;

FIG. 8 is a view showing sequence information necessary for executing the process control of FIG. 2;

FIG. 9 is a flowchart showing details of the process control of FIG. 7;

FIG. 10 is a selection program for determining whether or not to perform the dilution cut control for executing the process of FIG. 7;

FIG. 11 is a block diagram for explaining a first example of a concentration control method in a conventional thin film growth apparatus.

FIG. 12 is a block diagram for explaining a second example of the concentration control method in the conventional thin film growth apparatus.

FIG. 13 is a block diagram for explaining a third example of the concentration control method in the conventional thin film growth apparatus.

[Explanation of symbols]

R1, R2: reactor, PL6A: vent line, MFC
3 to MFC5: flow rate controller, 11: high frequency generator, 1
2, 13 ... main body of vapor phase growth apparatus, 12, 13, 12A,
13A: operation panel, 14: control unit, 14A: operation panel,
15: gas control device, 23: gas supply source.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Kenji Akai 8231, Eguchi, Tokuyama-shi, Tokuyama-shi, Yamaguchi Pref. 5 Tokuyama Ceramics Co., Ltd. (72) Inventor Toshikazu Miyamoto, Tokuyama, Tokuyama-shi, Yamaguchi No. 8231 No. 5 Inside Tokuyama Ceramics Co., Ltd. (72) Inventor Naoyo Nomura 8321 No. 5 in Tokuyama-shi, Tokuyama-shi, Yamaguchi Pref. (58) Fields surveyed (Int. Cl. ⁷ , DB name) H01L 21/205

Claims (1)

(57) [Claims] 1. A silicon substrate of glass or the like disposed within the reactor, diluted to a predetermined concentration were mixed by the mixer at least one of the material gas and the carrier gas from the gas supply source
The specified flow rate of the raw material gas
By merging the Yariagasu fed to the reactor, a thin film deposition apparatus for forming a thin film on the substrate by vapor deposition, between the mixer and the gas supply source, said mixer and said reaction furnace Between the mixer and the vent line, and the first, second, and third controllable gas flow rates can be controlled.
A raw material diluted with a carrier gas to a desired concentration by the mixer according to a set value of the second and third flow controllers, wherein the flow rate is controlled by the first flow controller. The gas is delivered to the separately delivered cap via the second flow controller.
In a thin film growth apparatus that can be supplied to a reaction furnace by being combined with a rear gas, a gas flow of a third flow controller connected to the vent line is configured to be able to be cut off independently, and the gas flow to the mixer is controlled.
The supply of the carrier gas is configured to be interruptable, and the first and second carrier gases are not diluted with the source gas from the gas supply source.
The flow rate is controlled by the flow controller and sent separately as above
A thin film growth apparatus characterized in that it can be supplied to a reactor by being combined with an incoming carrier gas .