JPS6077416A - Gas flow rate control apparatus for semiconductor vapor growth apparatus - Google Patents

Abstract

PURPOSE:To prevent defective product by connecting auxiliary controllers to all flow rate controllers of the various gas supply systems for the reaction furnace, programmably monitoring flow rate with the CPU and realizing epitaxial growth under the constant flow rate by changing over the flow rate controller to the auxiliary controller when a trouble occurs. CONSTITUTION:The flow rate controllers MFC8-10 are controlled by a processing program PP. In the PP9, the P type dopant Dp is sent through the MFC10 which is preset to the predetermined value from a chamber 16 through a valve PV23 and it is mixed with H2 supplied through the PV24. The mixed gas is branched to MFC9 and 8 preset to the predetermined values. In the PP9, the PV 19A is off and therefore the gas flows into the path PL6A and is then exhausted in mixing with H2+SiCl4. In the PP10, the PV19 turns ON, the mixed gas partly flows into the PL1A through the MFC8 and thereby a P type semiconductor is formed by the vapor growth method on the wafer placed within the furnace. The auxiliary MFC8'-10' which hold minimum flow rate are connected in parallel to the MFC8-10 and if a trouble occurs, they immediately operate CV to hold predetermined flow rate. With this constitution, reliability of program control for vapor growth method can be improved and generation rate of defective product can be lowered.

Description

[Detailed Description of the Invention] [Technical Field to which the Invention Pertains] The present invention relates to a semiconductor vapor phase growth apparatus, and in particular, to supplying various gases and adjusting the amount of R to be controlled in the process control of this type of apparatus. The present invention relates to a gas flow rate control device for controlling a Ryukei MIJ controller.

[Prior art and its problems]

2. Description of the Related Art Today, semiconductor vapor phase growth apparatuses are used for mass-producing semiconductor single crystals, which perform vapor phase growth on semiconductor wafers. In this semiconductor vapor phase growth apparatus, it is important to easily and reliably set the flow rate of the gas used, the temperature inside the reactor, etc. as the process progresses within the reactor.

From this perspective, the applicant first developed a reactor for performing vapor phase growth on a substrate such as silicon, a means for heating the substrate, and a reactor and each a gas source necessary for vapor phase growth. and the conduit network that connects between.

Valve devices provided on the pipe network for forming a pipe network to guide desired amounts of various gases to the reactor, and signals for controlling ON-OFF or the opening degree of these valve devices. In a semiconductor vapor phase growth apparatus configured with a control device that controls the valve device, the control device that controls the valve device is configured to control the time, the gas used and its flow rate, and the furnace temperature for specifying the vapor phase growth process in the reactor. We have developed a process control device that holds a process program group consisting of a series of process programs containing information about the valve device, and a system program that decodes this process program group to form a control signal for the valve device, and has filed a patent application. .

That is, the semiconductor vapor phase growth apparatus according to the patent application is
Mainly, a plurality of reactors can be programmably controlled by a common process control device. however,
This type of process control equipment that has been traditionally implemented is
Various control targets by hand? J! The fabricated t
The measured wafer is measured, and the Ti1l control target is readjusted according to the results. Therefore, there is a high possibility of making a mistake in the adjustment operation of the controlled object, and therefore there is a problem that the incidence of defective products increases. It's a shame, Ueno was created from the standpoint of preventing the occurrence of these defective products.
measurement and adjustment of the controlled object (C) requires sufficient attention to avoid mistakes, and has the disadvantage of requiring a great deal of labor on the operator.

However, when producing a desired semiconductor wafer using the above-mentioned vapor phase growth apparatus, vapor phase growth with the desired thickness and resistivity depends on the type of gas used, its flow rate, operation time, and temperature conditions of the reactor. You get layers. Therefore, in order to obtain the desired thickness and resistivity of a vapor-phase grown layer formed on a semiconductor wafer, the amount of source gas (5 IC
1a, 5iH2C1!2, etc.) and the amount of dopant gas (N gas such as B2146 or P gas such as PH) are determined together with the reference base gas amount (H2 gas, etc.), and the target of process control is determined based on these gas amounts. The control value of the flow rate controller is set.

Therefore, conventionally, when performing vapor phase growth of semiconductors using the flow rate controller, a piping system as shown in FIG. 1 is employed to control the supply of various gases to one reactor. That is, in FIG.
．． /2°/l/l, /7 and /r each indicate a gas chamber, in which N2°H is sequentially filled.
2, DH,, Dp and HC1! gas is injected into each. Further, reference numeral 20 indicates a bubbling chamber, and this chamber, XO, is filled with a liquid of SiC14 or 5iHC.

The conduit extending upward from the chamber 10 is provided with a pressure switch PS/ and a normally open valve PVt (hereinafter, a normally open valve will be referred to as -), which communicates with the valve PV7. 1. Similarly, in the conduit extending upward from chamber l-2, there is a pressure switch P82. A valve PV2 is provided and communicates with valve PVr. and the valves PV7 and pv
The outlet boats of r merge and are connected to the line PL/ via a flow controller MFC/.

There is also a gas merging valve PV/ on the pipe line PL/.

PV20 is installed between the reactor and the pipe PL/
A, PL,! The gas supplied to A is connected to the valve PV/5.
', PV, and 20 are excited to mix.

From the chamber 20, two pipes P are connected via a valve PV3.
LjA and PL3B are extended and connected to valve VCno. Hydrogen gas H2 is introduced into the boat Pθ of this valve VC/, and this gas) (2 is derived from the boat P2 and the arm Wr
It is introduced into the bubbling chamber 20 through P L 3 A and -fTPV3, and is discharged into the liquid 5iCJ4 to perform bubbling. Therefore, a mixed gas of vaporized S i cz 4 and N2 is generated in the space inside the chamber 20, and this gas passes through the valve PVJ on the pipe PLJB to the input port P3. of the valve VC/. The output capo P/ is led to the through pipe PIIA.

Flow rate controllers MFC-Hiroshi, MFCJ', and MFCt are connected to a conduit extending upward from the chamber /4' containing dopane (N) gas through valves PVj. The input side of these controllers MFC47~B is the hydrogen gas H2 pipe PL.
The dopant N gas mixed with the hydrogen gas H2 is connected to the output side through the multi-pipe line PLl.
Guided by A.

A similar piping system is configured for the conduit extending upwardly from the chamber/l containing the dopant N gas. In this case, valves PV23, PV, 2hiro and flow controllers M'FCg, MFCP.

It will be understood from the drawing that MFClo corresponds to each of the above controllers.

Further, a valve PVJA and a flow rate controller MFC7 are provided on the pipe extending from the chamber 7g that seals MCI gas, and are connected to one merging valve PV and 20 mixing boats. A conduit PLJ is connected to the upstream side of the flow rate controller MFC7 via a valve PVAB.

The flow rate controller configured and arranged in this way bl FC/~
10 (there is no MFC3; the same applies hereinafter) il'i is program-controlled by the control system shown in FIG. That is, the process control device 2-2 is fully equipped with a built-in CPU that gives commands to each flow rate controller based on a predetermined process program, and this process control device 2.2
A command value voltage is supplied to each flow rate controller MFC/-10 via a D/A converter, 2G. On the other hand, the outputs from the flow rate detectors DT, which are arranged several times in each flow rate controller MFC/~10, are taken out sequentially by the analog multiplexer 1/kuza 2, and are passed through all of these A/D converters 2♂ to the 70
2.2.

Next, regarding the control system of the flow rate controller shown in FIG. 1 and FIG.
The explanation will be based on a typical process program shown in the figure.

The contents of process program PP (1) are N2
Indicate Purge and inject N2 to FN/7/ for 3 minutes.
Supply at a flow rate of min. Therefore, in FIG. 1, nitrogen gas N2 is supplied from the chamber io to the valves PV/ and PV7.
and a flow rate controller MFCl, further through a valve PV/,
It enters the reactor R/ through the PV 20 and is purged through the reactor exhaust port. In this case, the flow rate FNt)
7min is given from the process control device 22 shown in FIG. 1 as a voltage command value for the flow rate controller MFC/.

Process Progera APP (,2) is N2 Purge
, and water bed gas H2 is supplied at a flow rate of FH, 2 J/min for 3 minutes. Hydrogen gas H2 has a valve and flow rate control 5P
V2, PVJ', MFC/, PV15i', Pv-20
After purging, the reactor R/ is charged, and purging is performed in the same manner as the N2 barge described above.

The following process program PP (3) [hereinafter referred to as PP (il)] indicates HEAT 0N (1), the supply rate of hydrogen gas H2 to the reactor is FH, 21/min, and the status of the 6 valves does not change. Then, the induction heating furnace is set to the first stage level and heated for 3 minutes to reach the first set temperature θ/.

Next, in the process program p p (p), the hydrogen gas H2 is heated at the first stage level for 3 minutes so that the set temperature θ° C. is reached while keeping the same flow rate.

Process program PP (J-1 is HC1!VENT
shows. In this case, the settings are 3 minutes, hydrogen gas
2 is F H, 21/min, HC1! is FH
The flow rate is CL7/min. Hydrogen chloride HC1! flows through valve PVAA, fill controller MFC7, valves PV, 20 and the interior of reactor R/ to the ventro.

HC/flow i FHCL l/min is the flow rate controller M
It is set by the voltage command value to FC7.

Process program PP (!;l is HCj'ETCJ
(indicates and continues for 3 minutes. For this reason, the
Hydrogen gas H2 at the merging valve PV20 for grams pp(t)
and is supplied to the reactor R/.

The process program PP(7) is +1(2Purge
, and continues for 3 minutes in the same manner as the process program P P (, ri).

The process program P P (,!') is HEAT
DOWN is indicated, and the temperature inside the reactor R1 is set from 62°C to 03°C. When this 3-minute process program PP(d) is completed, preparations for vapor phase growth are almost completed, and the process then moves to the process program PP(d).

P (9) 14, EP i
vENT (1), and in 3 minutes, the water bed moth xH2 was F
H, 2l/min.

Dopant P gas Dp as F D P co/1nin
, silica tetrachloride: I75iCj4k F S / g/m
Supply at a flow rate of in. Hydrogen gas H2 is supplied through valve PV, 2
→VC/→PVj→chamber, 20, a mixture of gaseous 5rC1a and [2 flows from this chamber, 20 to valve PV3-+VC/K'), pipe PII
A is supplied. In contrast, from chamber/l to valve PV
23 and flow controller MFC♂, M:IP, 07. M
Since the dopant P gas Dr is supplied through the entire FC10, this gas DP and the pipe line PL have reached <A.
2+S;, cz4 joins and greets VENT.

The process program P P (10) is EPi DE
PO is shown, and the flow rate of each gas is according to the process program pp (
Same as (2), valve PV/7 is in ON state. This state continues for 3 minutes. Therefore, the gas (Dp-t-H25iC7t) supplied to the pipe line PL/A is
/P, enters the reactor R/ through the main boat of Sarani valve Pv20, and performs full vapor phase growth of P-type semiconductor on the wafer on the susceptor. The growth reaction in this case is a reversible hydrogen reduction reaction as shown in the following equation.

5iC1a+2H22S1+HiroHCJIn this way, Sl is accumulated on the wafer. Dopan 1-
Phosphine PHs is usually used as p-gas DP. When 3 minutes have elapsed with this process program P P (10), the vapor phase growth ends.

Process program P P (//) ij, Hz
Purge, and the process program PP (,
Similar to 21, hydrogen gas H2 is FH21! Supply for 3 minutes at a flow rate of /min.

Process program P P (/, 2), P P
(/3), PP (/ is not used in this example.

The process program PP(lt) indicates HEATOFF and cuts off the power supply to the conductive heating coil.

In this case, the reason why the time was set to 3 minutes was to allow for the time required for the temperature inside the furnace to decrease. During this time, hydrogen gas H2 is also supplied at a flow rate of FH, 2 J/min.

The process program PP (/4) is )i2 Pur
ge, and similarly to the process program PP (, 21), hydrogen gas H2 is fed into the flow chamber at FH, 2t!/min for 3
Supply for minutes.

And process program PP (/7) iJ, N
2 Purge f and nitrogen gas N2 to FN/71/
Supply for 3 minutes at a flow rate of min.

According to the above process program 7m PP(/1 to PP(/7)), one step of semiconductor vapor phase growth is completed.

In addition, in the vapor phase growth reaction under process program control described above, the case where a P-type semiconductor is vapor-phase grown on a wafer is shown, but when an N-type semiconductor is vapor-phase grown, the dopant N gas in chamber 7F is DN Struggle PV, 5'
, PVy and R lid controller MFC1l, MFC, 3-1
The configuration is such that it is supplied via MF (li). In this case, the dopant N gas DN is B2H6 (Di bo
rane) is preferably used.

As mentioned above, when performing programmable process control for supplying various gases to one reactor in a semiconductor vapor phase growth apparatus, the role of the flow rate controller is extremely important. Moreover, this glaze flow rate controller is connected to the sensor mechanism and valve (
It is designed to automatically adjust the degree of opening and closing of the valve by comparing the flow rate detected by the sensor with the set current, and requires high control performance. Nevertheless, failures are likely to occur. Therefore, if a failure occurs in any of the flow rate controllers, the VC will immediately produce a defective product if a certain process is being executed. Since it only detects abnormalities in the flow cap of the controller and issues an alarm, it does not cause a huge loss in productivity and relies on manual work by the operator for post-processing work such as replacing a malfunctioning flow controller. Therefore, there is a small point that the operating efficiency is significantly reduced.

[Purpose of the invention]

An object of the present invention is to deposit N on a semiconductor substrate such as a silicon wafer.
In a semiconductor vapor phase growth apparatus that grows epitaxial tm of type or P type, failure detection of a flow rate controller used to programmably supply various gases required for predetermined vapor phase growth and control by the failed flow rate controller. There is an IC that provides a gas flow rate control device that can prevent the generation of defective products and improve the efficiency of batch operations by maintaining the flow rate of gas at an appropriate level.

[Key points of the invention]

The present invention provides a reactor for performing vapor phase growth on a substrate such as silicon, a means for heating the substrate, and a pipe network connecting the M reactor and various gas sources necessary for vapor phase growth. and valves and flow rate controllers provided on the pipe network for forming a pipe network for guiding desired amounts of various gases to the reactor;
These valves and flow rate controllers are connected to ON-OF'F or a process control device that provides a signal for controlling them, and the auxiliary flow "i-direct control" is connected to the flow first-class controller through a switching valve, respectively. The present invention is characterized in that a program is installed in the process control device that connects the flow rate controllers in parallel and instructs switching control of a switching valve that monitors the flow rate controller for a sweeping abnormality and switches to an auxiliary flow rate controller.

In other words, in the present invention, for a flow rate controller that controls the flow rate of various gases supplied to a reactor for vapor phase growth,
By connecting auxiliary flow section control valves in parallel and programmably executing flow rate monitoring of the flow rate controller and switching control to the auxiliary flow rate controller in the event of a flow rate abnormality, a semiconductor vapor phase growth apparatus can be realized. It is possible to improve the reliability of programmable process control, stabilize product quality, and improve productivity.

Therefore, in the gas flow rate control device for the semiconductor vapor phase growth apparatus of the present invention, the program that instructs the switching control of the switching valve that monitors the R amount abnormality of the flow rate controller and switches to the auxiliary flow rate controller is the flow rate control device. An abnormal state in which the flow rate of the gas to be controlled in the device is 10% or more of the set amount is determined, and when an abnormal state of the gas flow rate is determined, a switching control command is issued to the switching valve and the flow rate setting of the auxiliary flow rate controller is performed. It is preferable if the configuration is configured to perform the following.

[Embodiments of the invention]

Next, examples of the gas flow rate control device for a semiconductor vapor phase growth apparatus according to the present invention will be described in detail below with reference to the accompanying drawings and tables.

Figure ≠ shows a system diagram of the flow rate controller 1 (MFC, MFC, MFClo) for supplying a mixed gas of base gas 112 and dopant (P) gas DP to the reactor R/. . Note that the detailed piping system is supplemented.

However, the flow rate controller I (MFCr~MF
C10) performs a multi-control operation on the process programs PP(ri) and PP(10) of the process program group described above. That is, in the process program PP(ri).

Flow controller MFC from chamber/l via valve PV23
Dopant P gas DP is supplied to 10. in this case,
The flow rate controller MFC10 controls the flow rate to, for example, 300ca/
min and mixed with base gas H2 supplied via valve pv2. The mixed gas obtained in this way has a flow rate of 300 ac/m, for example, a flow rate of ff, 300 ac/m.
The configuration is such that the flow is divided into flow controllers MFC and MFC set to in. However, the process program PP (P
) Since the valve PV/T4 is in the OFF state, all the mixed gas flows through the flow rate controller MFC to the pipe P.
When the process program PP (10) is entered at H2+5iC1!4, the valve PV/RIA is turned ON, and a portion of the mixed gas flows through the flow rate controller MFCr to the pipe PL/A. It flows into the H2+5 IC 14 and is supplied to the reactor R/, where a P-type semiconductor is grown in a vapor phase on a wafer on a susceptor in the reactor R/.

Therefore, in this case, if any of the flow rate controllers MFC~10 fails and the set flow rate cannot be maintained stably, the component ratio of the mixed gas changes and the progress of vapor phase growth is inhibited due to the change in the amount of R. This makes it impossible to maintain a constant quality of the resulting product.

Therefore, in the present invention, for each of the flow rate controllers MFC to 10, for example, as shown in FIG.
Auxiliary flow controllers MFCr', MFCli'', MFC/O set to maintain the required minimum flow rate via
'f Connect and arrange in parallel.

When any of the flow rate controllers MFC to MFC10 detects a flow rate abnormality, the switching valve CV is immediately operated to maintain a predetermined flow rate in the auxiliary flow controller. .

Therefore, in the present invention, an auxiliary flow rate controller having the above-mentioned configuration is installed for each of the #L dividing controllers provided in the supply system of various gases for one reactor R/, and each of the above-mentioned flow rates is The CPU built in the flow control device 2.2 (see FIG. 1) programmably monitors flow rate abnormalities in the controllers, and commands switching control of the flow rate controllers in which abnormal conditions are detected.

Figure 2 shows how to monitor the abnormal state of the flow controller and check the auxiliary flow rate! 2 is a flowchart of a program stored in the CPU for controlling switching to the II device. That is,
Issues a quantity monitoring command to the operating flow rate controller, determines whether the controlled gas exceeds 10% of the set value, and if it exceeds ±/47% of the installed quantity, sends the corresponding assistance. It commands the flow rate controller to set a predetermined flow rate and also commands the operation of the switching valve. As a result, if the switching valve is activated and the flow is switched to the auxiliary flow controller, this is confirmed and the predetermined program is terminated.

The configuration of a process control system for executing these programs is shown in FIG.

〔Effect of the invention〕

As is clear from the embodiments described above, according to the present invention,
When controlling the various gases supplied to the reactor in a semiconductor vapor phase growth system using designated flow rate controllers based on a predetermined process program, flow rate abnormalities are programmably monitored, and if an abnormality is detected, parallel control is immediately performed. The gas flow rate to the product can be maintained stably by switching to the auxiliary flow controller connected to the auxiliary flow controller, which increases the reliability of control performance when performing programmable process control of semiconductor vapor phase growth equipment. It is possible to reduce the number of defective products and improve operational efficiency and productivity.

Especially according to the gas flow rate control device of the present invention.

In order to programmably execute the switching control of the switching valve that switches to one device, this kind of semiconductor In combination with a control device that performs programmable process control for each patch, such as a phase growth device, maintenance can be performed without requiring human intervention in the event of flow controller failure during batch operation, and product quality can be improved. Stability is achieved, and mass production of products and reduction of manufacturing costs can be easily realized.

Although the preferred embodiments of the present invention have been described above, it goes without saying that various design changes can be made without departing from the spirit of the present invention. .

[Brief explanation of the drawing]

Fig. 1 is a piping system diagram showing the gas supply system of the semiconductor vapor phase growth apparatus, Fig. 2 is a system diagram showing the control system of the flow rate controller connected to the gas supply system shown in Fig. 1, and Fig. 3 is a system diagram showing the control system of the flow rate controller connected to the gas supply system shown in Fig. 1. FIG. 2 is an explanatory diagram showing an example of a process program executed by the process control device provided in the control system shown in FIG. 2, and FIG. A system diagram showing an example, Fig. 3 is an explanatory diagram showing the connection state between the flow rate controller and the auxiliary R amount controller shown in Fig. FIG. 7 is a flowchart of a program that performs switching control. FIG. 7 is a block diagram showing the configuration of a process control system that executes the program shown in FIG. 10, /2. /41. /l, /I-=gas chamber buff 0...bubbling chamber, 2.2...process control device 2t...D/A converter MFC/~10...flow rate controller R/...reactor Cy...Switching valve PV,! J., PV211. , PV/PA,B
-, -Valve PL/A, PLAA...Pipeline FIG, 2 FIG, 3 Procedure Neichi Dosan (spontaneous) 11th Precept November 24, 1958 Commissioner of the Patent Office Kazuo Wakasugi 1, Incident Indication I %58 Patent Application No. 184955 2 Title of invention Gas flow rate control Fl device for semiconductor vapor phase growth equipment 3 Relationship to the person making the amendment Case Patent applicant address 2-11 Ginza 4-chome, Chuo-ku, Tokyo Issue name (345
) Toshiba Machine Co., Ltd. Representative Plate Material Separation 4, Agent (1)

Claims (1)

[Claims] (1) A reactor for performing vapor phase growth on a substrate such as silicon, means for heating the substrate, and a pipe network connecting the reactor and various gas sources necessary for vapor phase growth; Valves and flow rate controllers provided on the pipeline network for forming a pipeline network for guiding desired amounts of various gases to the reactor, and ON-OFF or control of these valves and flow rate controllers. an auxiliary flow controller is connected in parallel to each of the flow rate controllers via a switching valve, and the auxiliary flow rate controller monitors the flow rate abnormality of the flow rate controller; 1. A gas R amount control device for a semiconductor vapor phase growth apparatus, characterized in that a program for instructing switching control of a switching valve that performs switching is incorporated into the process control device. (2. In the gas flow rate control device according to claim 1, the program for instructing the switching control of the switching valve that monitors the flow rate abnormality of the flow rate controller and switches to the auxiliary flow rate controller is configured to control the flow rate. It determines an abnormal state in which the amount of gas to be controlled in the device is 10% or more of the set amount, and when an abnormal state of the gas flow rate is determined, it issues a switching control command to the switching valve and also controls the flow A gas flow rate control device for a semiconductor vapor phase growth apparatus configured to set the flow rate of the device.