JP2009245978A - Semiconductor manufacturing apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor manufacturing apparatus allowing appropriate countermeasures against heater disconnection to be taken by obtaining prediction information about it, in a continued state during heat treatment execution of a semiconductor manufacturing process such as formation of a thin film on a semiconductor wafer by heating a heater by carrying a current thereto. <P>SOLUTION: This semiconductor manufacturing apparatus equipped with a heater 1 for a heating process includes: a means of sampling the waveform of a drive current of the heater; a means of obtaining a resistance value of the heater 1 based on the sampling data thereof; a means of obtaining the amplitude of a noise component superposed on the drive current; and a means of determining heater disconnection prediction alarm based on the heater resistance value, the gradient of heater resistance value rise and the amplitude of the noise component. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a semiconductor manufacturing apparatus, and more particularly to a heater disconnection prediction in a semiconductor manufacturing apparatus provided with a heater for heat treatment.

  In manufacturing a semiconductor element, for example, a CVD apparatus provided with a heater for heat treatment is used. A semiconductor wafer such as a silicon wafer is accommodated in a heating furnace so that the furnace temperature becomes a predetermined value. A reactive gas is supplied into a heating furnace while controlling the amount of heat generated, and a thin film is formed on a semiconductor wafer.

  The internal temperature of the heating furnace for forming a thin film on a semiconductor wafer is controlled with high accuracy up to a high temperature of around 1300 ° C. with a repetition period of several hours to several tens of hours. Is continuously operated.

  As described above, the heater for heat treatment provided in the semiconductor manufacturing apparatus is operated under severe conditions, and thus has a relatively short life of 1 to 2 years.

  A user of a semiconductor manufacturing apparatus wants to use a heater for heat treatment as long as possible until just before the wire breaks, but if the heater breaks in the middle of forming a thin film on a semiconductor wafer, a maximum of 100 sheets during the thin film formation The semiconductor wafer that may exceed the limit may be wasted, and a great loss exceeding the replacement cost of the heater may occur. I want to avoid the heater disconnection.

By the way, Patent Document 1 describes a heater abnormality detection method for a semiconductor manufacturing apparatus.
JP 2000-223427 A

  The heater abnormality detection method for a semiconductor manufacturing apparatus described in Patent Document 1 executes a heater abnormality detection step for detecting a heater abnormality in a standby state before a semiconductor wafer is accommodated in a heating furnace. is there. Specifically, the presence / absence of an abnormality is determined based on the time until the temperature fluctuation reaches a predetermined value and the current value flowing through the heater.

  However, in the method described in Patent Document 1, the heater abnormality detection step for detecting the abnormality of the heater is executed in the standby state before the semiconductor wafer is accommodated in the heating furnace. It is performed once between batch units of a semiconductor manufacturing process operated at a repetition period of 10 to several hours from time.

  That is, according to the method described in Patent Document 1, the heater abnormality cannot be detected during the semiconductor manufacturing process in which the semiconductor wafer is housed in the heating furnace, and the semiconductor manufacturing process is being executed. It is not possible to take appropriate measures as soon as possible by obtaining predictive information on heater breaks in Japan.

  The present invention solves such a problem, and the object of the present invention is to break the heater in a continuous state during the heat treatment of the semiconductor manufacturing process such as energizing and heating the heater to form a thin film on the semiconductor wafer. An object of the present invention is to realize a semiconductor manufacturing apparatus capable of obtaining prediction information and taking appropriate measures.

In order to achieve such a problem, the invention according to claim 1 of the present invention is:
In a semiconductor manufacturing apparatus equipped with a heater for heat treatment,
Means for sampling the heater drive current waveform;
Means for determining the resistance value of the heater based on the sampling data;
Means for determining the amplitude of the noise component superimposed on the drive current;
Means for determining a heater breakage prediction alarm based on the heater resistance value, the rising slope of the heater resistance value, and the amplitude of the noise component,
It is characterized by having.

The invention according to claim 2 is the semiconductor manufacturing apparatus according to claim 1,
The drive current waveform of the heater is detected by a clamp probe.

The invention described in claim 3 is the semiconductor manufacturing apparatus according to claim 1 or 2,
The semiconductor manufacturing apparatus has a heater chamber configured as a horizontal furnace.

According to a fourth aspect of the present invention, in the semiconductor manufacturing apparatus according to the first or second aspect,
The semiconductor manufacturing apparatus has a heater chamber configured as a vertical furnace.

A fifth aspect of the present invention provides the semiconductor manufacturing apparatus according to any one of the first to fourth aspects,
The heater is driven by three-phase power.

  According to the present invention, the heater breakage prediction information can be obtained in a continuous state during the heat treatment of a semiconductor manufacturing process such as forming a thin film on a semiconductor wafer by energizing and heating the heater, and appropriate measures are taken. be able to.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of the present invention, and shows an example applied to a heater chamber configured as a horizontal furnace. The heater 1 is provided with four terminals 2 to 5 so as to be divided into three zones Z1 to Z3 along the longitudinal direction.

  Driving power is applied to the zones Z1 to Z3 of the heater 1 from the secondary windings W21 to W23 of the power transformer 9 via thyristor circuits 6 to 8 in which two thyristors are connected in parallel with opposite polarities. ing. That is, the terminal 2 is connected to the H-side end of the secondary winding W21 via the thyristor circuit 6, and the terminal 3 is connected to the L-side end of the secondary winding W21 and connected to the terminal 2 via the thyristor circuit 7. The L side end of the secondary winding W22 is connected, the H side end of the secondary winding W22 is connected to the terminal 4, and the H side end of the secondary winding W23 is connected via the thyristor circuit 8 to the terminal 4 5 is connected to the L-side end of the secondary winding W23.

  The primary windings W11 to W13 of the power transformer 9 are supplied with respective phases U, V, and W of commercial phase, for example, 50 Hz, three-phase power via the breaker 10. That is, the H-side end of the primary winding W11 is connected to the U-phase output terminal of the breaker 10, and the L-side end of the primary winding W12 is connected to the V-phase output terminal. The L side end is connected and the H side end of the primary winding W13 is connected, and the H side end of the primary winding W12 is connected to the W phase output terminal and the L side end of the primary winding W13 is connected. Is connected.

  Here, focusing on the drive currents i1 to i3 flowing in the zones Z1 to Z3 of the heater 1, the drive current i1 flows from the terminal 2 to the terminal 3 in the zone Z1, and the direction from the terminal 4 to the terminal 3 in the zone Z2. The drive current i2 flows through the zone Z3, and the drive current i3 flows from the terminal 4 to the terminal 5 through the zone Z3.

  These drive currents i1 to i3 can be measured by clamping the corresponding cables with the clamp probes 11 to 13. That is, when measuring the driving current i1, the cable of the terminal 2 is clamped by the clamp probe 11, and when measuring the driving current i2, the cables of the terminal 2 and the terminal 3 are clamped simultaneously by the clamp probe 12, and when measuring the driving current i3. Clamps the cable of the terminal 5 with the clamp probe 13. In measuring the drive current i2, the cable of the terminal 4 and the terminal 5 may be clamped simultaneously by the clamp probe 14 instead of the clamp of the cable of the terminal 2 and the terminal 3 by the clamp probe 12 at the same time. .

  The measurement signals of the drive currents i1 to i3 measured by the clamp probes 11 to 13 are input to the data collection device 15, and are sampled at a high speed with, for example, a sampling clock having a sampling period of 50 μs and stored as measurement data.

  The data processing device 16 performs data processing as described below in order to predict the disconnection of the heater 1 based on the measurement data stored in the data collection device 15.

  FIG. 2 is an external conceptual configuration diagram of the main part of FIG. In the heater chamber in which the heater 1 is wound around the inner wall surface, in the case of a diffusion process, a process gas is poured through the mass flow controller 17 while being heated to 400 to 1200 ° C. at normal pressure. The boat 19 on which the wafer 18 is loaded is taken into and out of the chamber from one open end of the chamber, and a predetermined heat treatment based on the recipe for the wafer 18 is performed. On the other hand, in the case of an LP-CVD (Low Pressure Chemical Vapor Deposition) process, the process is performed in a vacuum.

FIG. 3 is a flowchart for explaining a specific flow of data processing by the data processing device 16.
(1) First, the raw current waveforms of the driving currents i1 to i3 of about 100 A at the maximum flowing through the zones Z1 to Z3 of the heater 1 are measured. According to the knowledge of the applicants who conduct maintenance and inspection of semiconductor manufacturing equipment, as a cause of disconnection of the heater 1, heat is generated by the expansion and contraction of the heater wire whose end is fixed to the terminal due to heat. It is conceivable that stress due to strain is generated, cracks are generated in the strands, and a large current flows through the cracks, whereby an arc is generated and the cracks are accelerated. Although no noise component is superimposed on the current waveform until the crack is generated, a noise component with a considerably large amplitude is often superimposed just before the disconnection.

  Therefore, as shown in FIG. 1, the corresponding cables are clamped by the clamp probes 11 to 14, the waveforms of the drive currents i1 to i3 flowing through the zones Z1 to Z3 are picked up, and these output signals are picked up by the data collecting device 15. Is sampled at high speed, and the raw current waveform data is stored in the data processor 16. For example, by sampling with a sampling clock with a period of 50 μs, the superimposed noise component can be sufficiently captured as waveform data.

(2) In FIG. 3 again, in order to calculate the drive current value and resistance value of the heater 1, the data processing device 16 performs a moving average process on the raw current waveform data to remove noise components.
(3) Subsequently, RMS (Root Mean Square) calculation processing is performed on the waveform signal from which the noise component has been removed, and the drive current value of the heater 1 is calculated.
(4) Using this drive current value, a heater resistance value is calculated based on the heater voltage / heater current.

(5) The calculated heater resistance value is stored in a predetermined storage area of the data processing device 16.
(6) For the heater resistance value, the difference between the current measured value and the past measured value is obtained, and the slope of the heater resistance value rise is obtained.

  FIG. 4 (A) is an actual measurement diagram showing the change over time in the control output of the heater 1 at a set temperature of 1200 ° C. The solid line shows the transition of the zone Z1, the alternate long and short dash line shows the transition of the zone Z2, and the broken line shows the zone Z3. It shows the transition of. From these transitions, it can be confirmed that the control output of each zone tends to increase with the passage of date. Therefore, as shown in FIG. 4B, by setting an appropriate threshold value Rth with respect to the temporal change of the heater resistance, it is considered possible to perform a certain degree of disconnection prediction although high accuracy cannot be expected.

(7) In FIG. 3 again, the noise component is calculated by calculating the difference between the raw current waveform of (1) and the waveform of (2) from which the noise component has been removed.
(8) The difference between the calculated maximum value and minimum value of the noise component is calculated to calculate the amplitude value of the noise component.
(9) The calculated amplitude value of the noise component is stored in a predetermined storage area provided in the data processing device 16.

(10) The difference between the current measurement value and the past measurement value of the noise component amplitude value is obtained and collated with a preset alarm setting value, and the slope of the heater resistance value increase obtained in (6) is also predetermined. This is compared with the alarm set value and a heater breakage prediction alarm is determined.
(11) The determination result is displayed and output, for example, with the lighting color or lighting pattern of a lamp provided corresponding to each zone. Specifically, for example, in a normal state, the status display lamp is continuously lit green or completely turned off, and when it is determined as a sign of a disconnection, it is continuously lit yellow or blinking, and when a disconnection is detected, it is red. Continuous lighting or flashing.

  With such a configuration, the heater disconnection prediction information based on the quantified measurement data is obtained during the heat treatment of the semiconductor manufacturing process such as forming the thin film on the semiconductor wafer 18 by energizing and heating the heater 1. Therefore, the operator can take appropriate measures to suppress the cost based on the heater disconnection prediction information.

  In the above embodiment, an example of a horizontal furnace has been described. However, the present invention can also be applied to a vertical furnace.

  Further, it is known that when a crack occurs in the element wire of the heater 1 or when the crack expands, an acoustic wave (AE: Acoustic Emission) such as vibration or sound wave is accompanied. By measuring this AE as necessary, an improvement in the disconnection prediction accuracy can be expected.

  Moreover, although the example which drives a heater with 3 phase electric power was demonstrated in the said Example, this invention is applicable also when a heater is driven with single phase electric power.

  As described above, according to the present invention, it is possible to obtain predictive information on heater disconnection continuously even during the heat treatment of the semiconductor manufacturing process, and to realize a semiconductor manufacturing apparatus that can perform optimum operation at low cost.

It is a block diagram which shows one Example of this invention. It is an external appearance conceptual block diagram of the principal part of FIG. 4 is a flowchart illustrating a specific flow of data processing by the data processing device 16. It is an example figure of a time-dependent change of heater control output.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heater 2-5 Terminal 6-8 Thyristor circuit 9 Power transformer 10 Breaker 11-14 Clamp probe 15 Data collection device 16 Data processing device 17 Mass flow controller 18 Wafer 19 Boat

Claims (5)

In a semiconductor manufacturing apparatus equipped with a heater for heat treatment,
Means for sampling the heater drive current waveform;
Means for determining the resistance value of the heater based on the sampling data;
Means for determining the amplitude of the noise component superimposed on the drive current;
Means for determining a heater breakage prediction alarm based on the heater resistance value, the slope of the heater resistance value rise and the amplitude of the noise component,
A semiconductor manufacturing apparatus comprising:   2. The semiconductor manufacturing apparatus according to claim 1, wherein the drive current waveform of the heater is detected by a clamp probe.   The semiconductor manufacturing apparatus according to claim 1, wherein the semiconductor manufacturing apparatus includes a heater chamber configured as a horizontal furnace.   The semiconductor manufacturing apparatus according to claim 1, wherein the semiconductor manufacturing apparatus includes a heater chamber configured as a vertical furnace.   The semiconductor manufacturing apparatus according to claim 1, wherein the heater is driven by three-phase power.

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