JP3799144B2 - Microwave plasma processing equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention includes photoresist ashing (ashing), substrate surface etching or cleaning, substrate surface doping, substrate surface oxidation or nitridation, vapor phase chemical deposition (CVD) and sputtering, plasma polymerization on the substrate surface. It belongs to the technical field of the microwave plasma processing apparatus used for the above.
[0002]
[Prior art]
In the manufacture of semiconductor devices, the above-described plasma treatment process is employed.
[0003]
In particular, a plasma generated using a microwave represented by 2.45 GHz can be a high-density plasma having a plasma density of 1 × 10 ^{10 to} 1 × 10 ¹¹ ION · cm ⁻³ .
[0004]
With the progress of miniaturization and high integration in the recent semiconductor device manufacturing, the number of plasma processing steps is increasing, and there is a strong demand for improving the processing capability of plasma processing.
[0005]
A conventional microwave plasma apparatus uses a single chamber, a single microwave oscillator, a single exhaust system, and a single gas supply system to process single-wafer plasma, which is a substrate to be processed, one by one. Processing devices are common.
[0006]
The processing using such a single wafer plasma processing apparatus is roughly composed of the following steps. First, a step of replacing the atmosphere in the chamber with the atmosphere (about 20 seconds), a substrate replacement step of taking out the processed substrate from the chamber and placing the substrate before processing in the chamber (about 10 to 20 seconds), Evacuating the gas to a pressure of about 13 Pa to 27 Pa (about 20 seconds), introducing a process gas into the chamber to a predetermined pressure (about 5 seconds), and microwave energy to the chamber This is a step of performing plasma processing by putting it in the chamber.
[0007]
Thus, the time required for the steps other than the plasma processing step is about 55 to 65 seconds per substrate, and this time does not contribute to the actual manufacturing of the semiconductor device.
[0008]
In Japanese Patent Laid-Open No. 63-265892, as shown in FIG. 10, the microwaves oscillated from one microwave oscillator 1 are branched into two directions by a branching waveguide 2 and branched into two directions. An apparatus is described which leads to one chamber 2.
[0009]
In this apparatus, since the microwave oscillator is shared by the two chambers, the occupied floor area (footprint) of the apparatus is relatively small, but there is a technical process (1) to be solved as described later. .
[0010]
FIG. 11 shows another example of a conventional plasma processing apparatus.
[0011]
The microwave oscillated from the microwave oscillator is supplied to the chamber 3 through the rectangular waveguide 4. In the reaction chamber separated from the atmosphere by the quartz bell jar 8, the gas supplied from the gas supply system including the gas supply pipe 12 and the controller 13 generates glow discharge plasma by microwaves. An appropriate treatment is performed on the surface of the substrate W by the glow discharge plasma.
[0012]
Here, 5 is an isolator, 6 is a directional coupler, and 7 is an auto tuner. The exhaust pipe 10 and the valve 11 constitute an exhaust system connected to a vacuum pump (not shown).
[0013]
However, in order to uniformly process a substrate having a large surface to be processed, there is a technical problem (2) to be solved as described later.
[0014]
[Problems to be solved by the invention]
Technical issues (1)
In the apparatus described in Japanese Patent Laid-Open No. 63-265892 described above, since the plasma processing is simultaneously performed in the two chambers, the ratio of the time allocated for the plasma processing to the time required for the entire processing is different from the conventional one. Absent.
[0015]
Therefore, the operating rate of the microwave oscillator remained low.
[0016]
Technical course (2)
The microwave propagation mode by the rectangular waveguide is generally the TE ₀₁ mode, which has a feature that the electric field strength is increased on the short side of the waveguide.
[0017]
Therefore, the intensity of the plasma obtained thereby has a distribution according to the electric field intensity distribution of the microwave, and it is difficult to improve the uniformity of the plasma processing.
[0018]
[Means for solving the problems]
The present invention relates to a microwave plasma processing apparatus having a plurality of chambers for plasma processing an object to be processed and a microwave supply means for supplying microwaves for generating plasma. And a switching means for switching the microwave propagation path to the microwave propagation path leading to.
[0019]
The present invention also relates to a microwave plasma processing apparatus having a chamber for plasma processing an object to be processed and a microwave supply means for supplying a microwave for generating plasma. features and mode conversion means for converting a propagation mode of the microwaves in the TM ₀₁ mode of the circular waveguide is propagated to, that tapered cylindrical tube is provided between the mode conversion means and the chamber And
[0020]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a microwave plasma processing apparatus according to the present invention.
[0021]
Reference numeral 21 denotes switching means, and the microwave generated by the microwave oscillator 1 propagates to the switching means 21 via the rectangular waveguide 4. The switching means 21 selectively propagates the microwave to either the waveguide 28 or the waveguide 29 according to the setting, and supplies the microwave to the corresponding chamber 3R or chamber 3L.
[0022]
Reference numeral 22 denotes a common gas supply means for supplying process gas into the corresponding chambers 3R and 3L via the valve 23 or 24. 30 and 31 are valves for opening to the atmosphere.
[0023]
A common exhaust means 25 exhausts gas from the corresponding chamber via a valve 26 or 27.
[0024]
When the valve is opened and closed, the exhaust amount and the process gas supply amount are appropriately adjusted so that the pressure in the other chamber is not affected.
[0025]
FIG. 2 is a schematic sectional view of the switching means.
[0026]
The switching means includes an outer waveguide member 32 having two openings 34, 35, and 36 and an inner waveguide member 33 having a waveguide 37 inside.
[0027]
The member 33 can rotate at least 90 degrees, and FIG. 2 shows a state in which the opening 34 and the opening 35 are communicated and the opening 36 is blocked. At this time, the microwave propagating from the waveguide 4 to the opening 34 is propagated to the waveguide 28 from the opening 35 via the waveguide 37 having a corner inside, and enters the right chamber 3 in FIG. Supplied.
[0028]
If the corner forming member 33 is rotated 90 ° clockwise, the opening 34 and the opening 36 communicate with each other, and the microwave is supplied to the left chamber 3 in FIG.
[0029]
Although not shown, the exhaust means 25, gas supply means 22, valves 23, 24, 26, 27 switching means 21, oscillator 1 and the like are controlled by control means such as a computer (not shown).
[0030]
Next, the operation of the apparatus will be described.
[0031]
First, an object to be processed is placed in the right chamber 3R in FIG. 1, and a gate valve (not shown) is closed. The vacuum pump of the exhaust means 25 is operated to depressurize the chamber 3R through the valve 26. Next, the valve 23 is opened, and the process gas supplied from the gas supply means 22 is introduced into the chamber 3R and maintained at a predetermined process pressure. At this time, plasma processing is performed in the left chamber in the figure.
[0032]
When the plasma processing in the left chamber 3L ends, the setting of the switching means 21 is changed, and the propagation path is switched so that the microwave is propagated to the waveguide 28 side.
[0033]
Then, plasma processing is started in the right chamber 3R. When the plasma processing is performed in the right chamber 3R, the supply of the process gas in the left chamber 3L is stopped by closing the valve 24, and then the atmosphere release valve 31 is opened to change the atmosphere. Replaced with the atmosphere. Then, the gate valve is opened, and the processed object to be processed is taken out from the left chamber 3L. Instead, a new object to be processed is placed in the left chamber 3L, and the gate valve is closed. The subsequent steps are the same as the operation steps of the right chamber 3R described above, the valve 27 is opened again, the inside of the chamber is exhausted, and the process gas is supplied into the left chamber 3L through the valve 24.
[0034]
As described above, while plasma processing is performed in one chamber, steps such as replacement of an atmosphere such as release to the atmosphere, replacement of an object to be processed, exhaust, and introduction of a process gas can be performed in another chamber. Therefore, after the plasma processing in one chamber is completed, the plasma processing can be immediately performed in the other chamber. That is, when the plasma processing is performed in one chamber, the operation rate of the microwave oscillator is increased because the other chamber is in a standby state or is shifting to a standby state.
[0035]
Since the present invention can be applied to various plasma processing apparatuses from CVD and ashing with relatively high pressure to sputtering with low pressure, depending on the operating pressure conditions and the processing method in the chamber, the time required to reach the standby state and the actual plasma The processing time can vary greatly, and the operating rate may not reach 100%, but this is not deviated from the gist of the present invention.
[0036]
FIG. 3 shows a microwave plasma processing apparatus according to another embodiment of the present invention.
[0037]
The same components as those in the apparatus shown in FIG.
[0038]
The apparatus of FIG. 3 is characterized in that mode conversion means 40 for mode conversion of the microwave propagation mode to the TM ₀₁ mode of a circular waveguide is provided, and further connected to the chamber 3 via a tapered waveguide 41. It is in. Here, 42 is a pressure gauge.
[0039]
FIG. 4 shows an example of the mode conversion means 40 for converting the microwave propagation mode from the TE ₁₀ mode of the rectangular waveguide to the TM ₀₁ mode of the circular waveguide.
[0040]
The mode conversion means 40 has a shape in which the rectangular waveguide portion 43 and the cylindrical waveguide portion 44 are connected so as to intersect at a right angle. For example, the TE ₁₀ mode microwave propagated from the rectangular waveguide portion 43 is TM. _It is converted to ₀₁ mode and transmitted to the cylindrical waveguide 44 side.
[0041]
FIG. 5 shows a tapered waveguide 41, which is shaped like a truncated conical top.
[0042]
A circular opening 45 having an inner diameter of 110 mm has substantially the same shape as the outlet opening of the cylindrical waveguide 44 of the converting means 40, and a circular opening 46 having an inner diameter of 240 mm has substantially the same shape as the inlet opening of the chamber 3. . The length (height) is about 230 mm, for example.
[0043]
Conventionally, when plasma ashing is performed on photoresist of an 8-inch wafer using a microwave of 2.45 GHz, non-uniformity of about ± 20% may occur on the wafer surface. Therefore, the uniformity was improved to ± 10% by rotating the wafer in the plane. However, the plasma intensity non-uniformity is not improved. According to the present invention, since the electric field strength is radially symmetric from the center of the tube, plasma having a uniform intensity distribution can be generated.
[0044]
Thus, according to an embodiment of the present invention, the ashing rate of the photoresist on the 8-inch wafer without rotating the wafer in-plane is about 3 μm / second at a substrate temperature of 200 ° C., a microwave power of 1000 W, a pressure of about 80 Pa, and an oxygen flow rate of 450 sccm. Min and uniformity becomes ± 5% or less.
[0045]
Further, this apparatus does not require a magnetic field by an electromagnet or a permanent magnet.
[0046]
FIG. 6 is a schematic perspective view showing a microwave plasma processing apparatus according to another embodiment of the present invention.
[0047]
This apparatus can be regarded as a combination of the apparatus shown in FIG. 1 and the apparatus shown in FIG.
[0048]
This apparatus has two chambers 3R and 3L for performing plasma processing. Correspondingly, a stage 9 with a heater on which an object to be processed is placed, a tapered waveguide 41, a mode converter 40 and a rectangular waveguide are introduced. Two wave tubes 29 are provided.
[0049]
For example, a microwave of 2.45 GHz generated by the microwave oscillator 1 is propagated to the switch 21 through the rectangular waveguide 4. The rectangular waveguide 4 includes an isolator 5 having a dummy load, a power monitor 58, and a 4E tuner (not shown), and the propagation of the microwave is controlled.
[0050]
As shown in FIG. 2, the switch connects one of the left and right rectangular waveguides and the rectangular waveguide 4 using corners.
[0051]
For example, when plasma processing is performed in the left chamber 3L, the microwave is converted from the TE ₁₀ mode to the TM ₀₁ mode by the mode converter 40 and supplied to the chamber 3L via the circular tapered waveguide 41. .
[0052]
The configuration in the chamber 3L will be described later with reference to FIG.
[0053]
52 is a loading unit for loading a cassette containing a plurality of unprocessed objects to be processed, and 53 is an unloading unit for loading a cassette for accommodating a plurality of processed objects to be processed.
[0054]
54 is a preheater that pre-heats the objects to be processed one by one, and 55 is a cooler that places the objects to be processed one by one and cools them to room temperature.
[0055]
Reference numeral 56 denotes a transport unit having an arm 57 that transports the objects to be processed between the loading unit 52, the preheating unit 54, the chambers 3R and 3L, the cooling unit 55, and the unloading unit 53 one by one.
[0056]
Reference numeral 51 denotes control means including a computer for controlling operations of the oscillator 1, the switching device 21, the heater-added heat stage 9, the transfer means 56, the preheater, and the like.
[0057]
In FIG. 6, the gas supply system and the gas exhaust system are omitted.
[0058]
Although FIG. 7 shows a cross section of the left chamber 3L, the right chamber 3R has substantially the same configuration.
[0059]
The stage 9 which is a support means for the workpiece W is lowered by a drive means (not shown) in the direction of the arrow in the figure, and the inside of the chamber is opened. In this open state, the workpiece W is placed on the stage 9 and taken out from the stage 9 by the arm 57. Since the stage can move up and down while the positions of the chamber and the microwave supply mechanism are fixed, the substrate can be transferred in and out, so that the substrate can be easily converted.
[0060]
Further, since the processing gas is discharged toward the center of the reaction chamber through the openings 12P provided at a plurality of locations along the inner periphery of the chamber and is discharged from the suction hole 10p below the substrate, Uniformity is increased and there are few particles.
[0061]
FIG. 8 shows an exhaust system and a gas supply system.
[0062]
The process gas is supplied to the chambers 3R and 3L by the supply means 22 via the valve 23 or 24.
[0063]
30 and 31 are valves for opening to the atmosphere.
[0064]
A purge gas supply means 61 supplies a purge gas such as nitrogen into the chambers 3R and 3L via the valve 61 or 62.
[0065]
FIG. 9 shows the process flow of the two chambers 3R, 3L.
[0066]
In the chamber 3L, the valve 63 is opened, purge gas is introduced, and then the valve 31 is opened. Thus, the inside of the chamber 3L is replaced with air from the process gas atmosphere. (Step 70). Next, the chamber 3L is opened, the substrate as the object to be processed is taken out, and a new substrate is stored in the chamber 3L. (Step 71). The chamber 3L is exhausted by the exhaust means 25 (step 72). Process gas is then introduced through valve 24 to a processing pressure. (Step 73). During this process 70 to 73, plasma processing is performed in another chamber 3R. The time during which the microwave is actually introduced and the processing is performed is, for example, about 30 seconds to 60 seconds, and may be shorter than the time of step 74.
[0067]
Typical examples of the object to be processed according to the present invention include a silicon wafer and a compound semiconductor wafer for manufacturing an IC, and a substrate such as quartz or glass for manufacturing a display device.
[0068]
The plasma treatment performed according to the present invention includes ashing of a photoresist provided on a target object; etching or cleaning of the target object surface; formation of a film on the target object by CVD, sputtering, plasma polymerization, or the like; Examples include plasma doping on the surface of the processing object; oxidation or nitriding treatment on the surface of the processing object.
[0069]
The process gas used in the present invention is hydrogen, oxygen, nitrogen, He, Ne, Ar, Kr, Xe, NH ₃ , N ₂ O, fluorine, chlorine, SiH ₄ , Si ₂ H ₆ , SiCl ₄ , SiH _2. A normal ashing gas, etching gas, CVD gas, or sputtering gas selected from at least one selected from Cl ₂ , CF ₄ , CCl ₄ , NF ₃ , BF _{3 and the} like.
[0070]
The pressure in the chamber, specifically the pressure in the reaction chamber, may be selected from 133.3 Pa to 1.3 × 10 ⁻² Pa according to each processing condition.
[0071]
When ashing a novolak photoresist adhering to the Si wafer, O ₂ is used as a process gas, the pressure is kept at about 133.3 Pa to 13.3 Pa, and ashing is performed by oxygen plasma. At this time, the input power of the microwave is 1000 to 1400 W, the flow rate of O ₂ is 400 to 600 sccm, and the substrate temperature is appropriately 200 ° C. to 300 ° C. As a result, the ashing rate is 5 μm / min to 7 μm / min. As a result, ashing uniformity of about 5% can be obtained.
[0072]
When a silicon nitride film is deposited by the CVD method using this apparatus, SiH ₄ and N ₂ gas are used as process gases, and the pressure is maintained at about 13.3 Pa to 6.0 Pa, and the film is formed by plasma CVD.
[0073]
When cleaning an Si wafer with this apparatus, Ar is used as a process gas, and foreign matter (dirt) is cleaned by a sputtering effect of argon ions at a pressure of 133.3 Pa to 1.33 Pa.
[0074]
【The invention's effect】
According to the present invention, the operating rate of the microwave oscillator is improved, and the number of processed objects per unit time is increased compared to the conventional one.
[0075]
In addition, according to the present invention, plasma processing with high processing speed and high uniformity can be performed.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a microwave plasma processing apparatus according to an embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of a switch for switching a microwave propagation path.
FIG. 3 is a schematic view of a microwave plasma processing apparatus according to another embodiment of the present invention.
FIG. 4 is a schematic diagram of a mode converter used in the present invention.
FIG. 5 is a schematic view of a tapered tube used in the present invention.
FIG. 6 is a schematic view of a microwave plasma processing apparatus according to still another embodiment of the present invention.
7 is a schematic cross-sectional view around the chamber of the microwave plasma processing apparatus of FIG. 6. FIG.
8 is a schematic diagram showing a gas supply / exhaust system of the microwave plasma processing apparatus of FIG. 6. FIG.
FIG. 9 is a diagram showing a process of microwave plasma processing according to the present invention.
FIG. 10 is a diagram showing a conventional microwave processing apparatus.
FIG. 11 is a diagram showing a conventional microwave processing apparatus.

Claims (6)

In a microwave plasma processing apparatus having a plurality of chambers for plasma processing an object to be processed and a microwave supply means for supplying a microwave for generating plasma,
Characterized in that it comprises switching means for switching a microwave propagation path by rotating a waveguide member having a waveguide bent in the microwave propagation path from the microwave oscillator to the plurality of chambers. Microwave plasma processing equipment.   The microwave plasma processing apparatus according to claim 1, wherein a common gas supply unit and an exhaust unit are connected to the plurality of chambers.   Control means for performing processing in one of the plurality of chambers and controlling at least one of atmosphere replacement, substrate replacement, evacuation, and process gas introduction in another chamber The microwave plasma processing apparatus of Claim 1 which has.   When microwaves are supplied to one of the plurality of chambers, control is performed so that at least one of the atmosphere replacement, the substrate replacement, the exhaust, and the process gas introduction is performed in another chamber. The microwave plasma processing apparatus of Claim 1 which has a control means.   2. Plasma processing using the apparatus according to claim 1, wherein plasma processing of a substrate is performed in at least one of the plurality of chambers, and at the same time, steps before and after the plasma processing are performed in at least one of the other chambers. Method.   6. The plasma processing method according to claim 5, wherein the steps before and after are at least one step of atmosphere replacement, substrate replacement, exhaust, and process gas introduction.

Images