JP3082716B2 - Laser CVD apparatus and method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laser CVD apparatus, and more particularly, to a laser CVD apparatus used for correcting a defect of a photomask used for manufacturing a semiconductor IC or a liquid crystal display, or correcting a wiring of a liquid crystal substrate.

[0002]

2. Description of the Related Art A conventional laser CVD apparatus of this type is used for correcting defects such as a photomask. The structure of a conventional laser CVD apparatus includes a laser light source, an irradiation optical system having a laser irradiation function and a microscope function, a source gas supply unit for supplying a CVD source gas, and a source gas introduced into a laser beam irradiation unit on a substrate. And an XY stage for holding the substrate, a heater for holding the substrate and maintaining the substrate temperature at a predetermined temperature, and an XY stage for holding the heater. The heater that keeps the substrate temperature constant in this device
It is extremely important for maintaining the reproducibility of the CVD process.

Such a configuration is disclosed in, for example,
No. 248430. In this apparatus, a configuration in which a plate-shaped heater is provided below the substrate for heating the substrate is shown as an embodiment.

[0004]

However, in the case of a photomask for liquid crystal or the like, it is necessary to correct a very large substrate whose size reaches a maximum of about 1 mx 1 m.
For this purpose, the heater also needs to be increased in size. However, in the case of the large heater, the temperature distribution in the substrate surface is increased due to the variation in the heat generation distribution and the variation in the degree of contact between the heater and the substrate.
The temperature accuracy required for stabilizing D cannot be secured.

Further, it takes a long time until the substrate is stabilized in a predetermined temperature range after the substrate is set on the heater.

Further, there is a disadvantage that the large heater is expensive, and the increase in the equipment cost cannot be avoided.

An object of the present invention is to provide a laser CVD apparatus which can improve the temperature accuracy of a processing portion at a low cost and shorten the time required to raise a substrate to a predetermined temperature.

[0008]

Means for Solving the Problems Laser CVD of the present invention
Device includes a processing unit on the surface of the workpiece material gas feed gas supply section to stop supplying (1 in Figure 1) to (20 in FIG. 1) (2 in FIG. 1) is condensed to the processing unit A laser light source (23 in FIG. 1) for irradiating the laser beam and an objective lens (2 in FIG. 1).
And 4), the raw material gas (process portion 1) than the buffer gas heated to a high temperature (9 in Figure 1) in FIG. 1 (buffer gas supply unit to stop supplying sprayed to 20) of Figure 1 (in FIG. 1 1
0 ) and the buffer gas supply unit ( 10 in FIG. 1) is controlled to supply the buffer gas ( 9 in FIG. 1) to the processing unit (20 in FIG. 1) and heat the processing unit (20 in FIG. 1). Source gas (Fig. 1
The buffer gas (9 in Figure 1) when exceeding the temperature of 1) stops, the raw material gas supply unit (2) is controlled to the processing unit of FIG. 1 (of 20) in the raw material gas (Figure 1 1 ) Is supplied, and the temperature of the processing section (20 in FIG. 1) is reduced, and the raw material gas (20 in FIG. 1)
1 ) The control unit (see FIG. 1) for controlling the laser light source (23 in FIG. 1) to start laser beam irradiation after reaching the temperature of FIG.
21 ).

Further, a buffer gas supply section ( 10 in FIG. 1)
Is a second pipe (1 in FIG. 1) for guiding the buffer gas to the processing section.
5) The heated buffer gas (having a heater to maintain higher temperature temperature raw material gas 9 in FIG. 1) (1 in FIG. 1) (12 in Figure 1).

[0010]

Next, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic structural view of a laser CVD apparatus according to the present invention.

A source gas supply unit 2 for supplying a source gas 1 for performing CVD comprises a container 4 containing a source gas material 3, a carrier gas 5, a first valve 6, and a first pipe 7. . The container 4 stores a source gas material 3 which is a material of the source gas 1 for performing CVD. The temperature of the source gas 1 is determined by the required concentration (partial pressure) of the source gas 1, and the container 2 and a first pipe 7 described later are kept at that temperature by a heater (not shown). Raw material 3
For example, Cr (CO) ₆ is used. The source gas material 3 stored in the container 1 is heated and vaporized in the container 4, mixed with the carrier gas 5 supplied to the container 4, and mixed with the first pipe 7 provided with the first valve 6. Is supplied to the chamber 8 as the source gas 1. As the carrier gas 5, for example, Ar is used. The source gas 1 is kept at a predetermined temperature by a heater (not shown).

A buffer gas supply section 10 for supplying a buffer gas 9 kept at a high temperature is connected to the first pipe 7. The buffer gas supply unit 10 includes a flow rate controller 11, a heater 12, a temperature sensor 13, and a second pipe 15 provided with a second valve 14. The second pipe 15 is connected to the first pipe 7 on the downstream side of the first valve 6.

The buffer gas 9 is a chemically inert gas. For example, nitrogen gas, argon gas, or the like is used.

The flow controller 11 controls the buffer gas 9
And outputs the detection result to the connected control unit 21, and controls the flow rate of the buffer gas 9 based on a command from the control unit 21.

The heater 12 is provided downstream of the flow controller 11 and is driven by the temperature controller 16 to heat the second pipe 15 to heat the buffer gas 9.

The temperature sensor 13 is a sensor installed downstream of the heater 12 for detecting the temperature of the buffer gas 9. For example, a thermocouple is used.

A buffer gas 9 supplied into the chamber 8
And the raw material gas 1 is blown out from a nozzle 17 connected to the final end of the first pipe to a processing part 20 which is a part of the surface on the substrate 19. The processing portion 20 indicates a range of the surface of the substrate 19 which is heated to a predetermined temperature by the buffer gas 9.

Further, the control unit 21 determines the flow rate of the buffer gas 9, the temperature of the buffer gas 9, the first valve 6 and the second valve 14 based on conditions input by the operator.
The flow controller 11, the temperature controller 16, the first valve 6 and the second valve 1
4 and outputs a laser irradiation start signal.

Here, with respect to the determination of the temperature of the buffer gas 9, the flow rate of the buffer gas 9, and the opening / closing timing of the valve, the thickness of the substrate and the substrate temperature to be set at the time of performing the CVD are inputted to the corresponding buffer. It has a heating condition setting table 22 that outputs a gas temperature, a buffer gas flow rate, a blowing time from the start to a stop of the buffer gas spraying, and a laser irradiation start time from the stop of the buffer gas spraying to the start of laser beam irradiation. Read out these values corresponding to the substrate thickness and substrate temperature
If it is not recorded in the heating condition setting table 22, it is determined by performing a complementary calculation.

FIG. 3 shows an example of the heating condition setting table 22.

The buffer gas temperature is a control target temperature of the buffer gas, and the buffer gas flow rate is a flow rate of the buffer gas 9 controlled by the flow rate controller 11,
The spraying time is set after the second valve 14 is opened and the substrate 1
9 until the second valve 14 is closed to stop heating. Buffer gas temperature and buffer gas flow rate
The values of the range in which the temperature and the flow rate of the buffer gas 9 can be quickly set are set to the set values by the capabilities of the heater 12 and the flow rate controller 11, and furthermore, the input values are set for the substrate thickness of the substrate 19 and when performing CVD. An experiment is set in advance so that the temperature of the processing section 20 is suitable for a desired temperature in a short time in accordance with the substrate temperature to be set. In the experiment,
While monitoring the temperature of the processing section 20 on the substrate with the radiation thermometer, the time required for blowing the buffer gas 9 at the temporarily set buffer gas temperature and buffer gas flow rate to reach a predetermined temperature is measured. Then, the buffer gas temperature and the flow rate of the buffer gas were changed to measure the time required to reach the predetermined temperature, and the temperature of the processing section 20 was reduced to the predetermined temperature in the shortest time among various buffer gas temperature and buffer gas setting conditions. Are reached as the buffer gas temperature and the flow rate of the buffer gas. Further, for the same buffer gas temperature and flow rate of the buffer gas, there is a difference in the time required for the temperature of the processing section 20 to reach a predetermined temperature depending on the initial state such as the initial temperature of the substrate 19. The longest time of the variation is set as the set value of the spraying time.

The laser irradiation start time is a time from when the second valve 14 is closed to when a laser irradiation start signal is output, and is also set by an experiment and recorded in the heating condition setting table 22.

Also in this case, since the temperature of the processing section 20 when the second valve 14 is closed varies from various initial states in an actual apparatus, the raw material gas 1 at a predetermined temperature is blown to the processing section 20 to blow it. The maximum time required for the temperature to reach the set temperature is set as the set value of the laser irradiation start time.

Since the substrate temperature gradually decreases after the buffer gas is stopped, it is necessary that the temperature is higher than the temperature at which the CVD is performed when the blowing is stopped. is necessary. Therefore, after a predetermined time has elapsed from the laser irradiation start time, the laser irradiation is forcibly stopped.

Alternatively, the control unit 21 may be provided with a display panel or a warning device for generating a warning sound, and may generate a warning display or a warning sound.

An XY stage 18 on which a substrate 19 to be processed is placed and moved is installed in the chamber 8.

Laser light is emitted from a laser light source 23 and collected by an objective lens 24 through a window 25 onto a processing portion 20 on the surface of a substrate 19 which is a workpiece mounted on an XY stage 18. Be lighted. As the laser light source 23, for example, a laser device that emits the second harmonic of an Nd: YAG laser is used.

Further, the chamber 8 is provided with an exhaust system 26 for exhausting the raw material gas 1 and the buffer gas 9 blown out toward the processing section 20 in the chamber 8 and having passed through the processing section 20 to the outside. ing.

Further, the processing section 2 of the substrate 19 is further provided by an observation optical system 27 comprising an illumination light source, a camera and a monitor.
It is configured to be able to observe around zero.

Next, the substrate heating control operation of the laser CVD apparatus of the present invention will be described.

FIG. 2 is a flowchart showing the substrate heating control operation of the laser CVD apparatus of FIG.

A substrate 19 is set on an XY stage 18 in the chamber 8 by an operator, and the thickness of the substrate 19 and C
After input information such as a target substrate temperature to be set at the time of performing VD is input and the XY stage 18 positions the processing unit 20 of the substrate 19 at the irradiation position of the focused laser beam, Based on the information input by the operator, the control unit 21 calculates a buffer gas temperature, a buffer gas flow rate, a spraying time, and a laser irradiation start time to be set based on the heating condition setting table 22 (step S1). Then, with the first valve 6 closed, the second valve 14 is opened to start blowing the buffer gas 9 onto the substrate 19 in the chamber 8 (step S2). Here, while the buffer gas 9 is sprayed on the substrate 19, the flow rate is detected by the flow rate controller 11 and the flow rate of the buffer gas 9 is feedback-controlled so as to be the set flow rate.
The temperature of the buffer gas 9 is detected by the temperature sensor 13, feedback control is performed by the temperature controller 16 so that the buffer gas 9 becomes a set temperature, and heating of the processing portion 20 of the substrate 19 by the buffer gas 9 heated to a predetermined temperature. I do.

It is determined whether the predetermined time calculated in step S1 has elapsed since the start of the blowing of the buffer gas 9 (step S3). If the predetermined time has elapsed, the second valve 14 is closed and the blowing of the buffer gas 9 is performed. Is stopped (step S
4). If not, the spraying is continued, and step S3 is performed again.

The blowing is stopped, the first valve 6 is opened immediately, and the blowing of the source gas 1 to the substrate in the chamber 8 is started (step S5). Then, it is determined whether or not a predetermined time has elapsed after the blowing of the buffer gas 9 has been stopped (step S6). If the predetermined time has elapsed, a laser irradiation start signal is output, laser beam irradiation is started, and CVD is performed. (Step S7). If not, the spraying is continued and step S6 is performed again. When the CVD is completed, the first valve 5 is closed and the source gas 1 is stopped (step S8).

Then, the gas in the chamber 8 is exhausted by the exhaust system 26 (step S9).

A specific example of the above-described experimental form will be described.

When a photomask for liquid crystal having a thickness of 8 mm and a square of 60 cm is used as the substrate 17, as shown in FIG. 3, a buffer gas temperature, a buffer gas flow rate, a buffer gas blowing time, and a laser irradiation start time corresponding to the thickness of 8 mm. Are 50 ° C., 5 l / min, 2 min, and 1 min, respectively. Therefore, when the operator inputs the substrate thickness to the control unit 21, the respective settings are made as such.

The source gas material 3 is composed of Cr (CO) ₆
Is used, the container 4 and the first pipe 7 can obtain a saturated vapor pressure with a necessary raw material gas concentration of less than 0.3 Torr.
It is kept at ° C. The temperature of the source gas 1 sprayed on the substrate 19 is 30 ° C.

After blowing out the buffer gas 9 for 2 minutes, the second valve 14 is closed and the first valve 6 is opened.
One minute later, the temperature of the processing portion 20 of the substrate 19 becomes 30 ° C., so that one minute after opening the first valve 6, the control unit 21 outputs a laser irradiation start signal and outputs the laser light source 2.
No. 3 starts laser beam irradiation and performs CVD.

In the case of heating with a large heater as in the conventional apparatus, in the case of a photomask for a liquid crystal having a thickness of 8 mm and a square of 60 cm, the time required for the temperature rise takes 8 minutes or more. When CVD is performed, the time required for the temperature rise is 3 minutes as described above, and the remaining heat is completed, and the time is shortened.

Regarding the accuracy of the film thickness formed by the CVD, when the CVD is performed by heating with a large heater, for example, the CVD is performed at nine locations in the substrate, and the thickness of the film formed at each location is reduced. As a result of the measurement, the variation in the film thickness was ± 500 ° with respect to the average thickness of 2000 °. On the other hand, according to the laser CVD apparatus of the present invention, when the CVD was performed at nine places in the substrate under the above conditions. , The error is ±
It was 300 °, indicating that excellent stability was obtained.

The chamber 8 may be provided with a radiation thermometer for detecting the temperature of the substrate 19 in the vicinity of the processing section 20 in a non-contact manner.

In this case, the heating condition setting table 22
Does not require the set values of the blowing time and the laser irradiation start time, and in contrast to the operation of the above-described embodiment, in step S4, the temperature of the processing portion 20 of the substrate 19 is reduced by the blowing of the buffer gas 9 in the processing condition. When the temperature exceeds the temperature, the second valve 14 is closed. In step S6, when the source gas 1 is started to be blown and the temperature of the processing portion 20 of the substrate 19 reaches the temperature of the processing condition again, the laser beam Is started in that irradiation is started and CVD is performed.

According to this configuration, the temperature can be set with high accuracy even when the substrate temperature is higher than usual, for example, when a close place on the substrate 19 is continuously corrected.

When the radiation thermometer is not used, a longer time of the buffer gas is blown to take account of the variation due to the initial state, and the substrate temperature greatly exceeds the set substrate temperature. When the temperature exceeds the set temperature, the blowing of the buffer gas can be stopped immediately, so that the temperature can be raised in a short time.

[0047]

As described above, the laser C of the present invention is used.
Since the VD apparatus heats the processed part on the substrate by blowing the heated buffer gas, the time required to heat the substrate to a predetermined temperature can be shortened. Since the temperature can be set with high precision, it is possible to make the formed film thickness uniform.

In addition, since the buffer gas is heated by heating the pipe for guiding the buffer gas to the processing section, a large plate-like heater is not required. Laser CVD
An apparatus can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of laser CVD according to the present invention.

FIG. 2 is a flowchart showing a substrate heating control operation of the laser CVD apparatus of FIG.

FIG. 3 is an example of a heating condition setting table according to the laser CVD apparatus of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Source gas 2 Source gas supply part 3 Source gas material 4 Container 5 Carrier gas 6 First valve 7 First piping 8 Chamber 9 Buffer gas 10 Buffer gas supply part 11 Flow controller 12 Heater 13 Temperature sensor 14 Second valve Reference Signs List 15 second pipe 16 temperature controller 17 nozzle 18 XY stage 19 substrate 20 processing unit 21 control unit 22 heating condition setting table 23 laser light source 24 objective lens 25 window 26 exhaust system 27 observation optical system

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C23C 16/00-16/56 H01L 21/205 H01L 21/285 H01L 21/31-21/318

Claims (7)

(57) [Claims] 1. A material gas supply means for supplying and stopping a material gas to a processing part on a surface of a workpiece, a laser irradiation means for irradiating a laser beam focused on the processing part, A high-temperature gas supply means for blowing and supplying a high-temperature gas heated to the processing section to supply and stop the processing section, and controlling the high-temperature gas supply section to supply the high-temperature gas to the processing section to heat the processing section; When the temperature of the raw material gas is exceeded, the high-temperature gas is stopped, the raw material gas is supplied to the processing part by controlling the raw material gas supply means, and the temperature of the processing part is reduced to the temperature of the raw material gas. A laser control unit for controlling the laser irradiation unit later to start irradiation of the laser beam. 2. The high-temperature gas supply unit includes a heating unit that heats a pipe that guides the high-temperature gas to the processing unit and keeps the temperature of the high-temperature gas higher than that of the raw material gas. Laser CVD apparatus. 3. The laser CVD apparatus according to claim 2, wherein said high-temperature gas supply means has a flow controller for controlling a flow rate of said high-temperature gas. 4. The controller according to claim 1, wherein the controller controls a temperature controller and a flow controller in accordance with the input information on the workpiece to control supply and stop timings of the raw material gas and the high-temperature gas. The laser CVD apparatus according to claim 3, wherein 5. The controller according to claim 1, wherein the controller controls the temperature of the high-temperature gas, the flow rate of the high-temperature gas, the time from the start to the stop of the supply of the high-temperature gas, and the temperature of the high-temperature gas. 5. The laser CVD apparatus according to claim 4, further comprising a heating condition setting table for determining a laser irradiation start time for starting the irradiation of the laser beam after the supply is stopped. 6. A temperature sensor for detecting the temperature of the processing section in a non-contact manner and outputting the detected temperature to the control section, wherein the control section is configured to make the temperature of the processing section exceed the temperature of the raw material gas. When it is recognized that the supply of the high-temperature gas is stopped, the supply of the source gas is started, and after the fact that the temperature of the processing unit has reached the temperature of the source gas, the irradiation of the laser beam is started. The laser CVD apparatus according to claim 4, wherein: 7. A laser CVD method for supplying a raw material gas to a processed portion on the surface of a workpiece and irradiating the processed portion with a focused laser beam, wherein a high-temperature gas maintained at a temperature higher than the temperature of the raw material gas. the said processing unit and heated by blowing toward the working section stops blowing of the hot gas when exceeding the temperature of the feed gas the
A laser CVD method, wherein the supply of a source gas is started, and the irradiation of the laser beam is started after the temperature of the processing section decreases to reach the temperature of the source gas.