JP6507701B2 - Light processing apparatus and light processing method - Google Patents

Description

  The present invention relates to a light processing device and a light processing method. More specifically, the present invention includes, for example, photo ashing treatment of a resist in a manufacturing process of a semiconductor, liquid crystal, etc., removal treatment of a resist attached to the pattern surface of a template in a nanoimprint apparatus, dry treatment of a glass substrate for liquid crystal, silicon wafer, etc. The present invention relates to a light processing apparatus and a light processing method suitable for cleaning processing, smear removal (desmearing) processing in a printed circuit board manufacturing process, and the like.

Conventionally, for example, light ashing processing of resist in manufacturing process of semiconductor, liquid crystal, etc. removal processing of resist adhering to the pattern surface of template in nanoimprint apparatus, dry cleaning processing of glass substrate for silicon, silicon wafer etc., printed substrate manufacturing A light processing apparatus and a light processing method using ultraviolet light are known as a light processing apparatus and a light processing method used for smear removal (desmear) processing and the like in a process. In particular, an apparatus or method using active species such as ozone or oxygen radicals generated by vacuum ultraviolet radiation emitted from an excimer lamp etc. is suitably used because it can perform predetermined processing more efficiently in a short time. It is done.
For example, Patent Document 1 proposes a method in which a substrate is irradiated with ultraviolet light as desmearing of a via hole, and irradiation of ultraviolet light onto a substrate on which a via hole is formed in an atmosphere containing oxygen is proposed.

International Publication No. 2014/104154

As a result of intensive investigations, the present inventors irradiated ultraviolet light to a substrate through (1) gas such as oxygen or ozone, or gas containing oxygen or ozone, etc. for ultraviolet treatment for desmear treatment. (2) It has been found that the processing efficiency is improved by moving the processing gas so as to flow on the substrate rather than sealing in the processing chamber.
However, as a result of experiments, the speed at which the smear is removed (desmear processing speed) is lower than the flow of the processing gas in the peripheral area of the substrate near the air supply port. It has been found that it is slower than the inner region, that is, unevenness occurs in the substrate in the smear removal process.
An object of the present invention is to suppress processing unevenness in a substrate.

In order to solve the above-mentioned subject, one mode of a light processing device concerning the present invention is provided with a light source part which emits light, and a processing part by which a processed object is exposed to light emitted from the light source part. A processing unit configured to treat the processing object in which the processing object is held and exposed to the light in the atmosphere of the processing gas, and the processing gas passes while being exposed to the light and travels toward the processing region; A preparation area where placement of the processing object is prohibited, wherein the bottom surface facing the light source section is further away from the light source section compared to the surface of the object to be treated facing the light source section; Prepare.
Here, the “processing gas” is a gas that processes the object to be processed, and is a gas that obtains processing capacity by being exposed to light from the light source unit. A preferable combination of light and processing gas is, for example, a combination of vacuum ultraviolet light and oxygen. When oxygen is exposed to vacuum ultraviolet light, oxygen radicals (active species) and ozone are generated to oxidize the surface of the object to be treated and attached matter.

  According to the light processing apparatus according to the present invention, the processing gas whose processing capacity is obtained by passing through the preparation area reaches the processing area to process the object to be processed, so the periphery of the substrate close to the air supply port The difference in processing speed and the like between the partial area and the downstream inner area is suppressed, and the processing unevenness is also suppressed. In addition, since the bottom of the preparation area is separated from the light source unit as compared to the surface of the object to be treated, the size of the preparation area can be reduced, which contributes to the downsizing of the apparatus.

Further, in the light processing device, it is preferable that the preparation area has a flow passage cross-sectional area larger than that of the processing area. Thus, the length of the preparation area can be shortened in the direction along the flow of the processing gas.
Further, in order to solve the above problems, in the light processing method according to the present invention, a preparation step of irradiating the processing gas passing through the preparation area with light emitted from a light source, and preparation following the preparation area. Irradiating the light emitted from the light source onto the object to be processed disposed in the atmosphere of the processing gas having a flow passage cross-sectional area smaller than that of the processing region and having a flow velocity higher than that of the preparation region; Go through.
According to such a light processing method, processing unevenness in the substrate can be suppressed, and the size of the preparation area can be suppressed.

  According to the light processing apparatus and the light processing method of the present invention, processing unevenness in the substrate is suppressed.

It is a schematic block diagram which shows the light processing apparatus of this embodiment. It is a cross-section figure which shows the rough structure of a board | substrate. It is a figure which shows the 1st step of the effect | action in a desmear process. It is a figure which shows the 2nd step of the effect | action in a desmear process. It is a figure which shows the 3rd step of the effect | action in a desmear process. It is a figure which shows the last step of the effect | action in a desmear process. It is a figure which shows the effect | action in a preparatory area | region. It is a graph showing the relationship between ultraviolet irradiation and the concentration of the active species. It is a schematic block diagram which shows the light processing apparatus of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described based on the drawings.
FIG. 1 is a schematic configuration view showing the light processing apparatus of the present embodiment. In the present embodiment, as an example of the light processing apparatus, an application example to a desmear processing apparatus is shown.
(Configuration of light processing device)
The light processing apparatus 100 accommodates therein a processing unit 20 for holding and processing the substrate W inside, and a plurality of ultraviolet light sources 11 emitting, for example, vacuum ultraviolet light, and the substrate W of the processing unit 20 receives the ultraviolet light from the ultraviolet light source 11. And a light emitting unit for emitting light. The light irradiation unit 10 corresponds to an example of the light source unit according to the present invention, and the processing unit 20 corresponds to an example of the processing unit according to the present invention. The light of the ultraviolet light source 11 is irradiated almost equally to the entire effective irradiation area R0 substantially corresponding to the full width of the reflecting mirror 13. For convenience of illustration, the thickness of the substrate W is shown to be considerably larger than the actual thickness.

  The light irradiation unit 10 includes a box-shaped casing 14, and a window member 12 made of, for example, quartz glass, which transmits vacuum ultraviolet rays, for example, is airtightly provided on the surface located on the lower side of the casing 14. An inert gas such as nitrogen gas, for example, is supplied from the supply port 15 to the inside of the light irradiation unit 10, and the inert gas atmosphere is maintained. A reflecting mirror 13 is provided above the ultraviolet light source 11 in the light irradiation unit 10, and reflects the light emitted from the ultraviolet light source 11 to the window member 12 side. The window member 12 corresponds to an example of the window plate according to the present invention.

  The ultraviolet light source 11 emits, for example, vacuum ultraviolet light (ultraviolet light having a wavelength of 200 nm or less), and various known lamps can be used. For example, there are a xenon excimer lamp (wavelength 172 nm) and a low pressure mercury lamp (wavelength 185 nm) in which a xenon gas is sealed, and among them, for example, a xenon excimer lamp is preferable as one used for desmear treatment.

  The processing unit 20 is provided with a stage 21 facing the window member 12 of the light irradiation unit 10, which holds the substrate W subjected to the ultraviolet irradiation treatment (desmear treatment) on the surface thereof by suction. An outer peripheral groove 21 a is provided on the outer peripheral portion of the stage 21, and the O-ring 22 is sandwiched between the outer peripheral groove 21 a and the window member 12 of the light irradiation unit 10 to thereby form the light irradiation unit 10 and the processing unit 20. Are assembled airtight. A thermal resistance heater (not shown) is incorporated in the stage 21, and the entire substrate W on the stage 21 is heated in the desmearing process.

  An air supply port 21b for processing gas supply is provided at one side (right side in FIG. 1) of the stage 21 and an exhaust port 21c is provided at the other side (left side in FIG. 1). ing. Although one air inlet 21 b and one air outlet 21 c are illustrated in FIG. 1, the stage 21 is provided with a plurality of air outlets 21 b and a plurality of air outlets 21 c. The plurality of air supply ports 21b are arranged in the direction perpendicular to the paper surface of FIG. 1, and the plurality of exhaust ports 21c are also arranged in the direction perpendicular to the paper surface of FIG. A processing gas supply unit (not shown) is connected to each air supply port 11 to supply a processing gas. Further, an exhaust means (not shown) is connected to each exhaust port 12.

  Here, as the processing gas, for example, a mixed gas of oxygen gas, oxygen and ozone or water vapor, a gas in which an inert gas or the like is mixed with these gases, etc. can be considered, but an oxygen gas is used in this embodiment. It shall be. The processing gas is supplied from the air supply port 21 b and discharged from the exhaust port 21 c while the substrate W is irradiated with the ultraviolet light from the light irradiation unit 10. The processing gas traveling from the air inlet 21b to the air outlet 21c flows between the window member 12 and the substrate W from the right to the left in FIG.

In the stage 21, a step 21 d is provided in a region R2 on the upstream side (right side in FIG. 1) of the flow of processing gas, and the placement of the substrate W in the region R2 on the stage 21 is prohibited . The stage 21 is provided with a protrusion 21e on the side of the exhaust port 21c, and the substrate W is mounted on the stage 21 so as to abut on the protrusion 21e.
In the following description, in the area on the stage 21, the area R1 on which the substrate W is placed and processed is referred to as a processing area R1, and the area R2 on which the placement of the substrate W is prohibited is referred to as a preparation area R2. There is a case. Such a processing area R1 corresponds to an example of the processing area according to the present invention, and such a preparation area R2 corresponds to an example of the preparation area according to the present invention.

  The upper surface of the step 21 d forms the bottom of the preparation area R 2, and the bottom is located at a position farther from the light emitting unit 10 compared to the surface of the substrate W facing the light emitting unit 10. That is, in the processing area R1 and the preparation area R2, the preparation area R2 is wider in the vertical direction in the drawing (the direction intersecting the flow of the processing gas). Therefore, the flow velocity of the processing gas in the preparation region R2 is slower than the flow velocity of the processing gas in the processing region R1.

(Board structure)
Although the substrate W having various structures is used as the substrate W to be processed by the light processing apparatus 100, a simplified structural example will be described here.
FIG. 2 is a cross-sectional view showing a schematic structure of the substrate W. As shown in FIG.
The substrate W is, for example, an intermediate wiring substrate material on the way of manufacturing a multilayer wiring substrate for mounting a semiconductor element such as a semiconductor integrated circuit element.
In the multilayer wiring board, in order to electrically connect one wiring layer to another wiring layer, a via hole extending through one or more insulating layers in the thickness direction is formed. In the manufacturing process of the multilayer wiring board, the via hole 33 is formed by removing a part of the insulating layer 31 by performing, for example, laser processing on the wiring substrate material in which the insulating layer 31 and the wiring layer 32 are stacked. Be done.

However, smear (residue) S caused by the material of the insulating layer 31 adheres to the surface of the bottom and side portions of the formed via hole 33. If the plating process is performed in the via hole 33 in a state where the smear S remains attached, a connection failure between the wiring layers may be caused. For this reason, a desmear process of removing the smear S attached to the via hole 33 is performed on the wiring substrate material (substrate W) on which the via hole 33 is formed.
When the substrate W is placed on the stage 21 shown in FIG. 1, the via hole 33 is placed so that the opening of the via hole 33 faces the light irradiation unit 10, that is, the smear S is exposed to the ultraviolet light from the ultraviolet light source 11. Be placed.

(The procedure of desmear processing)
Next, referring back to FIG. 1, the procedure of the desmear process performed by the light processing apparatus 100 will be described.
First, a substrate W to be processed is transported from outside the processing unit 20 into the processing unit 20 and placed on the stage 21. The substrate W is held on the stage 21 by vacuum suction or the like. Thereafter, the processing gas is supplied to the processing unit 20 from the air supply port 21 b by the processing gas supply unit.
Simultaneously with the supply of the processing gas, the ultraviolet light source 11 is turned on, the irradiation unit 10 irradiates the processing unit 20 with the ultraviolet light, and the substrate W is irradiated with the ultraviolet light through the processing gas.

The processing gas irradiated with ultraviolet light generates active species such as ozone and oxygen radicals, for example, and reacts with the smear in the via hole to remove it, as will be described in detail later. A gas such as carbon dioxide produced by the reaction of the processing gas and the smear is carried downstream on the flow of the newly supplied processing gas, drawn from the exhaust port 21c and exhausted by the exhaust means. .
The processed substrate W is removed from the stage 21 and carried out of the processing unit 20.

(Function of desmear processing)
Here, the detailed action in the desmear process will be described.
3 to 6 are diagrams showing each step of the action in the desmear process.
In the first step shown in FIG. 3, oxygen contained in the processing gas is irradiated to the processing gas supplied from the air supply port as shown by the arrow pointing downward from the upper side of the drawing. The active species 34 such as ozone and oxygen radicals (here only oxygen radicals are shown) are generated. The active species 34 enter the via hole 33 of the substrate W.
In the second step shown in FIG. 4, the active species 34 react with the smear S in the via hole 33 to decompose a part of the smear S, and the ultraviolet rays are irradiated to the smear S and a part of the smear S is It is disassembled. Such decomposition of the smear S generates, for example, a reaction product gas 35 such as carbon dioxide gas or water vapor.

Then, in the third step shown in FIG. 5, the reaction product gas 35 flows from the air supply port side (right side in FIG. 5) and is discharged from the via hole 33 by the new processing gas containing the activated species 34 (FIG. To the left of the As the reaction product gas 35 is discharged, a new processing gas containing the activated species 34 enters the via hole 33.
As a result of repeated irradiation of ultraviolet rays, entry of active species 34, and discharge of reaction product gas 35, smear is completely removed from the via holes 33 in the final stage shown in FIG. The reaction product gas 35 flushed out of the via hole 33 is carried on the flow of the processing gas on the substrate W, and is discharged from the exhaust port 21 c shown in FIG. 1.

The light treatment process shown in FIGS. 3 to 6 corresponds to an example of the treatment process according to the present invention.
As described above, in the desmear process, the irradiation of ultraviolet rays generates active species such as oxygen radicals and ozone, for example, to enter the via holes 33 and irradiate the ultraviolet rays themselves into the via holes 33 for improving the processing efficiency. is important. Therefore, the distance between the window member 12 and the substrate W shown in FIG. 1 is preferably, for example, 1.0 mm or less, particularly preferably 0.5 mm or less, and more preferably 0.3 mm. It is an extent. As a result, oxygen radicals and ozone can be stably generated, and vacuum ultraviolet rays reaching the surface of the substrate W can be made to have a sufficient intensity (light amount).

(Operation in the preparation area)
By the way, in the conventional light processing apparatus, since it is important to efficiently use the ultraviolet light emitted from the light irradiation unit 10, in general, the region to which the ultraviolet light of the radiation intensity effective for the processing is irradiated is the substrate W Is covered, but it is not set to illuminate a wider area.
Therefore, in the conventional apparatus, in the peripheral area near the air supply port, it is considered that the new processing gas is swept downstream by the ultraviolet light before the generation of the active species with a sufficient concentration. Therefore, the concentration of active species reaching the via holes is low in the peripheral region, and the processing speed of desmearing is slower than the inner region located downstream of the processing gas, resulting in uneven processing in the substrate. Conceivable.

On the other hand, in the light processing apparatus 100 shown in FIG. 1, the placement of the substrate W is prohibited in the preparation area R2 in which the step 21d is provided on the stage 21. Light is emitted similarly.
FIG. 7 is a diagram showing the operation in the preparation area.
In the preparation region R2 in which the step 21d is provided on the stage 21, ultraviolet rays from the light irradiation unit are irradiated to the processing gas 36, which is, for example, oxygen gas, and active species 34 such as ozone and oxygen radicals are generated. .

  Since the substrate W is not present in the preparation region R2 (ie, there is no smear), the concentration of the generated active species 34 is gradually increased while being pushed downstream by the newly supplied processing gas 36 and stabilized. Do. That is, the preparation area R2 is an area that plays a role of irradiating the processing gas 36 with ultraviolet light to stabilize the concentration of the active species 34. Further, since the preparation region R2 has a deep bottom compared to the treatment region R1, the flow velocity of the treatment gas passing through the preparation region R2 is low, and the treatment gas is sufficiently exposed to the light from the light irradiation unit 10 at a short distance. The Rukoto.

On the other hand, if the bottom of the preparation area R2 is too deep, the amount of the reached ultraviolet light may be insufficient near the bottom of the preparation area R2 and the concentration of the active species 34 may not increase. The present inventors have conducted various experiments and calculations, and the upper and lower width of the preparation area R2 (that is, the distance from the window member 12 to the step 21d shown in FIG. 1) is 10 mm or less, preferably 5 mm or less, particularly preferably 0. I got the conclusion that it should be about 4 mm to 3.0 mm.
The processing gas, which is stabilized by increasing the concentration of the active species 34 in the preparation region R2, reaches the top of the substrate W with its activity maintained, enters the via hole, reacts with the smear, and is removed. Since the concentration of the activated species 34 of the processing gas is high and stable at the stage of reaching the substrate W, the processing speed at each portion of the substrate W is fast at any portion from the upstream to the downstream of the processing gas flow Uneven processing in the substrate W is suppressed.

The process in the preparation area shown in FIG. 7 corresponds to an example of the preparation process according to the present invention.
In addition, in FIG. 7, a mode that an ultraviolet-ray is irradiated to oxygen and oxygen radical which is active species is generate | occur | produced is shown typically as an example. However, ozone is also generated as an active species, and when ozone is contained in the processing gas, oxygen radicals are also generated from ozone by ultraviolet irradiation. When the processing gas contains water vapor or hydrogen peroxide, irradiation with ultraviolet light generates hydroxyl radicals which are active species.
The effects in the preparation region R2 described in FIG. 7 similarly occur in any of various processing gases and active species, and the processing unevenness in the substrate W is suppressed.

Next, the length of the preparation area in the direction along the flow of the processing gas is considered.
FIG. 8 is a graph showing the relationship between UV irradiation and the concentration of active species.
The horizontal axis of the graph of FIG. 8 indicates the irradiation time of ultraviolet light, and the vertical axis of the graph indicates the concentration of ozone which is the active species. Further, in the example shown in FIG. 8, oxygen is used as the processing gas, vacuum ultraviolet light having a wavelength of 172 nm is used as ultraviolet light with an intensity of 250 mW / cm ² , and the stage is heated to 150 ° C.

  The concentration of the active species (ozone) increases as the irradiation time increases from zero seconds, but as the concentration increases, the amount of elimination due to reaction between the active species also increases. As a result, for example, the concentration is stabilized at a concentration of about 3%. In the graph of FIG. 8, the concentration of the active species is stable at an irradiation time of about 0.5 seconds, but as a result of intensive investigations by the inventors, such concentration stability of the active species is Although the temperature of the processing gas causes some change, it was realized by irradiation with ultraviolet light for about 0.5 seconds, and it was found to be about 1.0 second at the longest.

Further, it was also found that the concentration stability occurs similarly in the case of oxygen radicals.
Therefore, the length of the preparation area is set to a length that requires a passing time of 0.5 seconds or more and 1.0 seconds or less according to the flow velocity of the processing gas. Specifically, the flow velocity of the processing gas in the processing region R1 needs to be maintained at a certain height, for example, about 50 to 500 mm / s, in order to efficiently discharge the exhaust gas generated in the processing from the processing region R1. Flow rate is adopted. As described above, the distance between the window member 12 and the substrate W in the processing region is preferably 1.0 mm to 0.3 mm, and the distance from the window member 12 to the step 21 d in the preparation region is 3.0 mm to 0 In view of the fact that .4 mm is desirable, it has been found that a short distance of 200 mm or less is sufficient for the length of the preparation area under typical conditions.

  That is, by narrowing the distance between the window member 12 and the substrate W in the processing region, it is possible to maintain an early flow rate at which rapid gas exchange (exhaust gas removal and supply of new active species) can be achieved on the substrate W. . On the other hand, in the preparation area, the distance from the window member 12 to the step 21 d is made longer than the distance between the window member 12 and the substrate W, so that the preparation area is not long (the device is enlarged). A long flow of light can be applied to the processing gas 36 to achieve a slow flow rate that can generate sufficient active species.

Next, a second embodiment will be described.
FIG. 9 is a schematic block diagram showing the light processing apparatus of the second embodiment.
The light processing apparatus 200 according to the second embodiment is the same as the embodiment shown in FIG. 1 except that the structure of the stage 21 in the preparation area is different, and therefore the description thereof will not be repeated. In FIG. 9 as well, the thickness of the substrate W is shown considerably larger than the actual thickness for the sake of convenience of illustration.
There is also a thick substrate exceeding 2 mm as a multilayer wiring substrate, and in the second embodiment, processing of such a thick substrate W is assumed.

  In the second embodiment, the surface 21f of the stage 21 in the processing area R1 is at a position lower than the surface 21g of the stage 21 in the preparation area R2 (that is, the lower position in the figure), and the substrate W is placed on the lower surface 21f. The placement of the substrate W is prohibited on the higher surface 21g. As described above, in the second embodiment, the surface 21g of the stage 21 in the preparation region R2 is high, but when comparing the widths in the vertical direction between the processing region R1 and the preparation region R2, as in the first embodiment, the processing region R1 The preparation area R2 is wider than that. For this reason, also in the second embodiment, as described in FIG. 7, the concentration of the active species is increased and stabilized in the preparation region R2, so that processing unevenness in the substrate W is suppressed and the length of the preparation region R2 Is short enough.

Next, experimental examples conducted to confirm the effects of the present invention will be described.
(Experimental example)
An optical processing apparatus according to the present invention having the following specifications was manufactured with reference to the configuration shown in FIG.
[Stage 21]
Dimensions: 755 x 650 mm, thickness 20 mm
Material: Aluminum Upper and lower width of preparation area: 1.0 mm
Length of preparation area: 40 mm
Heating temperature: 150 ° C
[UV light source 11]
Xenon excimer lamp Emission length: 700 mm
Width: 70 mm
Input power: 500 W
Number of lamps: 7 Vacuum UV irradiation time: 300 seconds

[Window member 12]
Dimensions: 755 x 650 mm, thickness 5 mm
Material: Quartz glass Distance between the window member and the substrate: 0.3 mm
[Substrate W]
Structure: An insulating layer is laminated on a copper substrate, and a via hole is formed in the insulating layer Dimensions: 500 mm × 500 mm × 0.5 mm
Thickness of insulating layer: 30 μm
The diameter of the via hole: 50 μm
[Conditions such as processing gas]
Processing gas: oxygen concentration 100%
Processing gas flow rate: 1.0 L / min

In the light processing apparatus of such a specification, about 1.2 seconds were required for the processing gas to pass through the preparation area, and processing unevenness in the substrate W did not occur.
In the above description, although an application example to a desmear processing apparatus is shown as an example of the light processing apparatus of the present invention, the light processing apparatus of the present invention includes, for example, a light ashing processing apparatus, a resist removal processing apparatus and a dry processing apparatus. The present invention may be applied to a cleaning treatment apparatus and the like.

  DESCRIPTION OF SYMBOLS 100 ... light processing apparatus, W ... board | substrate, 10 ... light irradiation part, 20 ... processing part, 11 ... ultraviolet light source, 12 ... window member, 21 ... stage, R1 ... processing area, R2 ... preparation area

Claims (3)

A light source unit that emits light;
A processing unit to which an object to be processed is exposed to light emitted from the light source unit;
The processing unit
A processing region in which the object to be processed is held and exposed to the light in an atmosphere of a processing gas;
The preparation area is a preparation area in which the disposition of the object to be treated is prohibited while passing through the treatment gas while being exposed to the light, and the bottom surface facing the light source part is a part of the object to be treated. A preparation area which is further from the light source compared to the surface facing the light source;
Equipped with
The light source unit includes a window plate that transmits light,
The processing unit includes a mounting table that faces the window plate and has a step,
The object to be processed is placed on an upper stage closer to the window plate among the steps of the mounting table,
The light processing apparatus, wherein the lower side of the step of the mounting table which is far from the window plate among the steps of the mounting table is the bottom surface.   The light processing apparatus according to claim 1, wherein the preparation area has a flow passage cross-sectional area larger than that of the processing area. Among the steps of the mounting table having a step facing the window plate of the light source provided with the window plate transmitting light, the processing gas passing through the preparation region having the bottom located at the lower side far from the window plate A preparatory step of irradiating light emitted from the light source;
Said processing said object to be processed object placed in an atmosphere of a gas high flow velocity than said preparation region in the processing region in which the processing object is placed on the upper closer to the window pane of the step of the mounting table Irradiating the light emitted from the light source;
The light processing method characterized by passing through.

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