JP6459578B2 - Optical processing apparatus and optical processing method - Google Patents

Description

  The present invention relates to an optical processing apparatus and an optical processing method. More specifically, the present invention relates to, for example, resist ashing treatment in a manufacturing process of semiconductors, liquid crystals, etc., removal of resist adhering to the pattern surface of a template in a nanoimprint apparatus, dry glass substrates for liquid crystals, silicon wafers, and the like. The present invention relates to an optical processing apparatus and an optical processing method suitable for cleaning processing, smear removal (desmear) processing in a printed circuit board manufacturing process, and the like.

Conventionally, for example, resist ashing processing in the manufacturing process of semiconductors, liquid crystals, etc., removal processing of resist adhering to the pattern surface of the template in the nanoimprint apparatus, dry cleaning processing of glass substrates and silicon wafers for liquid crystals, printed circuit board manufacturing As an optical processing apparatus and an optical processing method used for removing smear (desmear) in a process, an optical processing apparatus and an optical processing method using ultraviolet rays are known. In particular, an apparatus and method using active species such as ozone and oxygen radicals generated by vacuum ultraviolet rays radiated from an excimer lamp or the like can be used preferably because a predetermined treatment can be performed more efficiently and in a short time. Has been.
For example, Patent Document 1 proposes a method of irradiating a substrate with ultraviolet rays as a via hole desmear treatment method, and proposes irradiating a substrate with via holes formed with ultraviolet rays in an atmosphere containing oxygen.

International Publication No. 2014/104154

As a result of diligent study, the inventors of the present invention have (1) irradiating the substrate with ultraviolet rays via a gas such as oxygen or ozone or a gas containing oxygen or ozone. (2) It has been found that the processing efficiency is increased by moving the processing gas so as to flow on the substrate rather than sealing it in the processing chamber.
However, as a result of experiments, the present inventors have found that the speed at which smear is removed (desmear processing speed) in the peripheral area of the substrate close to the air inlet is downstream of the flow of the processing gas. It has been found that it is slower than the inner region, in other words, the smear removal process is uneven in the substrate.
An object of this invention is to suppress the process nonuniformity in a board | substrate.

In order to solve the above-described problem, an aspect of the light processing device according to the present invention includes a light source unit that emits light, and a processing unit that exposes an object to be processed to the light emitted from the light source unit, A processing unit holds the object to be processed and is exposed to the light in an atmosphere of a processing gas, and passes the processing gas while being exposed to the light and travels toward the processing region. And a preparation area where the arrangement of the processing object is prohibited.
Here, the “processing gas” is a gas for processing an object to be processed, and is a gas that obtains processing capability 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 and deposits of the object to be treated.

According to the optical processing apparatus of the present invention, the processing gas that has obtained the processing capability by passing through the preparation area reaches the processing area and processes the object to be processed. Differences in processing speed and the like between the partial area and the downstream inner area are suppressed, and processing unevenness is also suppressed. If a sufficiently long preparation area is provided, processing unevenness in the substrate can be prevented.
In the optical processing apparatus, the processing unit forms a mounting table on which the object to be processed is mounted, and a forming tool for preventing the mounting of the object to be processed on a part of the mounting table and forming the preparation area And are preferably provided.
According to such an optical processing apparatus, the preparation region is reliably formed by the forming tool.

Further, in the light processing apparatus, the light source unit includes a window plate that transmits light, and the processing unit includes a mounting table that faces the window plate and on which the object to be processed is mounted. It is also preferable that the preparation area is an area sandwiched between the window plate and a portion of the mounting table on which the object to be processed is not placed.
According to such an optical processing apparatus, the flow of the processing gas in the preparation region is stabilized, and as a result, the processing capability obtained by the processing gas is also stabilized.

Moreover, in order to solve the said subject, the one aspect | mode of the optical processing method which concerns on this invention is followed by the preparatory process which irradiates the light emitted from the light source to the process gas which is passing the preparatory area, and the said preparatory area | region. And a processing step of irradiating the object to be processed disposed in the processing gas atmosphere in the processing region with the light emitted from the light source.
Since the processing gas is processed in the processing step after the processing gas has obtained processing capability in the preparation step, processing unevenness in the substrate is suppressed.

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

It is a schematic block diagram which shows the optical processing apparatus of this embodiment. It is a sectional structure figure showing a schematic structure of a 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 preparation area | region. It is a graph showing the relationship between the irradiation of ultraviolet rays and the concentration of active species. It is a schematic block diagram which shows the optical processing apparatus of 2nd Embodiment.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram illustrating an optical processing apparatus according to the present embodiment. In this embodiment, an application example to a desmear processing apparatus is shown as an example of an optical processing apparatus.
(Configuration of light processing equipment)
The light processing apparatus 100 stores therein a processing unit 20 that holds and processes the substrate W and a plurality of ultraviolet light sources 11 that emit, for example, vacuum ultraviolet rays, and the substrate W of the processing unit 20 receives the ultraviolet light source 11 from the ultraviolet light source 11. A light irradiator 10 for irradiating light. The light irradiation unit 10 corresponds to an example of a light source unit according to the present invention, and the processing unit 20 corresponds to an example of a processing unit according to the present invention.

The light irradiation unit 10 includes a box-shaped casing 14, and a window member 12 made of, for example, quartz glass that transmits vacuum ultraviolet rays, for example, is hermetically provided on a lower surface of the casing 14. An inert gas such as nitrogen gas is supplied from the supply port 15 into the light irradiation unit 10 and is maintained in an inert gas atmosphere. A reflecting mirror 13 is provided above the ultraviolet light source 11 in the light irradiation unit 10, and reflects light emitted from the ultraviolet light source 11 toward the window member 12. This window member 12 corresponds to an example of a window plate according to the present invention. The light from the ultraviolet light source 11 is irradiated almost uniformly on the entire effective irradiation region R0 substantially corresponding to the entire width of the reflecting mirror 13.
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) enclosing xenon gas, a low-pressure mercury lamp (wavelength 185 nm), etc. Among them, for example, a xenon excimer lamp is suitable for use in desmear treatment.

  The processing unit 20 is provided with a stage 21 that attracts and holds the substrate W to be subjected to ultraviolet irradiation processing (desmear processing) on the surface thereof, facing the window member 12 of the light irradiation unit 10. This stage 21 corresponds to an example of a mounting table according to the present invention. An outer peripheral groove 21 a is provided in 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, so that the light irradiation unit 10, the processing unit 20, Is airtightly assembled. A thermal resistance heater (not shown) is incorporated in the stage 21, and the substrate W on the stage 21 is heated during the desmear process.

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

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

  The stage 21 is provided with a convex portion 21d in a region R2 on the upstream side (the right side in FIG. 1) in the flow of the processing gas. Yes. In other words, a step is formed on the stage 21 between the region R1 where the substrate W is placed and held and the region R2 where placement is prohibited. The convex portion 21d corresponds to an example of a forming tool according to the present invention.

In the following description, among the regions on the stage 21, the region R1 on which the substrate W is placed and processed is referred to as the processing region R1, and the convex portion 21d is provided and the placement of the substrate W is prohibited. R2 may be referred to as a preparation area R2. Such a processing region R1 corresponds to an example of a processing region according to the present invention, and such a preparation region R2 corresponds to an example of a preparation region according to the present invention.
In the present embodiment, since the protrusion amount of the convex portion 21d (that is, the height of the step of the stage 21) is equal to the thickness of the substrate W, the gap through which the processing gas flows is equal in both the processing region R1 and the preparation region R2. Thus, the flow of the processing gas from the air supply port 11 toward the exhaust port 12 is stabilized. Further, the vacuum ultraviolet rays irradiated from the light irradiation unit 10 reach both the processing region R1 and the preparation region R2 with the same intensity.

(Substrate structure)
As the substrate W to be processed by the optical processing apparatus 100, substrates W having various structures are used. Here, a simplified structure example will be described.
FIG. 2 is a sectional view showing a schematic structure of the substrate W. As shown in FIG.
The substrate W is an intermediate wiring board material in the middle of manufacturing a multilayer wiring board for mounting a semiconductor element such as a semiconductor integrated circuit element.
In a multilayer wiring board, a via hole extending through one or a plurality of insulating layers in the thickness direction is formed in order to electrically connect one wiring layer and another wiring layer. In the manufacturing process of the multilayer wiring board, via holes 33 are formed by removing a part of the insulating layer 31 by, for example, applying laser processing to the wiring board material in which the insulating layer 31 and the wiring layer 32 are laminated. Is done.

However, smear (residue) S resulting from the material constituting the insulating layer 31 adheres to the bottom and side surfaces of the formed via hole 33. If plating is performed in the via hole 33 with the smear S still adhered, poor connection between wiring layers may be caused. For this reason, a desmear process for removing the smear S adhering to the via hole 33 is performed on the wiring board 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 substrate W 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 ultraviolet rays from the ultraviolet light source 11. Placed.

(Desmear processing procedure)
Next, returning to FIG. 1, the procedure of desmear processing executed by the light processing apparatus 100 will be described.
First, the substrate W to be processed is transferred 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 21b by the processing gas supply means.
Simultaneously with the supply of the processing gas, the ultraviolet light source 11 is turned on, the ultraviolet rays are irradiated from the irradiation unit 10 toward the processing unit 20, and the substrate W is irradiated with the ultraviolet rays through the processing gas.

The processing gas irradiated with ultraviolet rays generates active species such as ozone and oxygen radicals, and reacts with and removes smear in the via hole, as will be described in detail later. A gas such as carbon dioxide generated by the reaction of the processing gas and smear is carried downstream along the flow of the newly supplied processing gas, drawn into the exhaust port 21c, and discharged by the exhaust means. .
The processed substrate W is removed from the stage 21 and carried out of the processing unit 20.

(Desmear treatment effect)
Here, a detailed operation in the desmear process will be described.
3-6 is a figure which shows each step of the effect | action in a desmear process.
In the first stage shown in FIG. 3, the oxygen contained in the processing gas is irradiated by irradiating the processing gas supplied from the air supply port with ultraviolet rays as indicated by an arrow pointing downward from above in the drawing. As a result, ozone or oxygen radicals (only oxygen radicals are shown here) which are active species 34 are generated. The active species 34 enters the via hole 33 of the substrate W.
In the second stage shown in FIG. 4, the active species 34 reacts with the smear S in the via hole 33 and a part of the smear S is decomposed, and even when the smear S is irradiated with ultraviolet rays, a part of the smear S is formed. Disassembled. By the decomposition of the smear S, a reaction product gas 35 such as carbon dioxide gas or water vapor is generated.

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

The optical processing steps shown in FIGS. 3 to 6 correspond to an example of the processing steps according to the present invention.
As described above, in desmear treatment, for example, active species such as oxygen radicals and ozone are generated by ultraviolet irradiation and enter the via hole 33 and the ultraviolet ray itself is irradiated into the via hole 33 in order to improve 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 mm or less, and particularly preferably 0.5 mm or less. Thereby, oxygen radicals and ozone can be generated stably, and the vacuum ultraviolet rays reaching the surface of the substrate W can be set to a sufficiently large intensity (light quantity).

(Operation in the preparation area)
By the way, in the conventional light processing apparatus, since it is important to efficiently use the ultraviolet rays irradiated from the light irradiation unit 10, in general, the region irradiated with the ultraviolet rays having the radiation intensity effective for the processing is the substrate W. Is not set to irradiate a wider area.
Therefore, in the conventional apparatus, it is considered that in the peripheral region close to the air supply port, the active species having a sufficient concentration is generated by the ultraviolet rays and is pushed downstream by the new processing gas. Therefore, in the peripheral region, the concentration of active species reaching the via hole is low, the desmear processing speed is slower than the inner region located downstream of the processing gas, and as a result, processing unevenness occurs in the substrate. Conceivable.

On the other hand, in the optical processing apparatus 100 shown in FIG. 1, the preparation area R2 is formed by providing the projection 21d on the stage 21 and prohibiting the placement of the substrate W, but this preparation area R2 is formed. In the same manner as in the processing region R1, light is irradiated.
FIG. 7 is a diagram illustrating the operation in the preparation area.
In the preparation region R2 formed by the projection 21d of the stage 21, for example, the processing gas 36, which is oxygen gas, is irradiated with ultraviolet rays from the light irradiation unit, and active species 34 such as ozone and oxygen radicals are generated. .

  Since there is no substrate W in the preparation region R2 (that is, there is no smear), the generated active species 34 is pushed by the newly supplied processing gas 36 and flows downstream, and the concentration gradually increases and stabilizes. To do. That is, the preparation region R2 is a region that plays a role of stabilizing the concentration of the active species 34 by irradiating the processing gas 36 with ultraviolet rays. In the present embodiment, since the processing gas flows through a temporally and spatially stable gap sandwiched between the stage and the window member, the flow of the processing gas is also stabilized. As a result, the concentration of the active species 34 is reliably stabilized. Turn into.

  The processing gas stabilized by increasing the concentration of the active species 34 in the preparation region R2 reaches the substrate W while maintaining the activity, enters the via hole, and reacts with the smear to be removed. Since the concentration of the active species 34 of the processing gas is high and stable at the stage of reaching the substrate W, the processing speed at each location of the substrate W is fast at any location from upstream to downstream of the processing gas flow. Processing unevenness in the substrate W is suppressed.

The process in the preparation area shown in FIG. 7 corresponds to an example of the preparation process referred to in the present invention.
FIG. 7 schematically shows, as an example, how oxygen radicals, which are active species, are generated by irradiating oxygen to ultraviolet rays. However, ozone is also generated as an active species, and when the processing gas contains ozone, oxygen radicals are also generated from ozone by ultraviolet irradiation. Further, when the processing gas contains water vapor or hydrogen peroxide, hydroxyl radicals that are active species are generated by ultraviolet irradiation.
For any of these various processing gases and active species, the action in the preparation region R2 described with reference to FIG. 7 occurs in the same manner, and processing unevenness in the substrate W is suppressed.

Next, the preferred size of the preparation region (the length in the direction along the flow of the processing gas) will be examined.
FIG. 8 is a graph showing the relationship between ultraviolet irradiation and the concentration of active species.
The horizontal axis of the graph in FIG. 8 indicates the irradiation time of ultraviolet rays, and the vertical axis of the graph indicates the concentration of ozone that is an active species. In the example shown in FIG. 8, oxygen is used as a 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 extinction amount due to the reaction between the active species also increases. As a result, for example, the concentration becomes stable 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. As a result of extensive studies by the inventors, such concentration stability of the active species is, for example, the intensity of ultraviolet rays and Although there was some change in the temperature of the processing gas, it was found that it was realized by ultraviolet irradiation for about 0.5 seconds and was about 1.0 seconds at the longest.

Also, it was found that concentration stabilization occurs similarly in the case of oxygen radicals.
Accordingly, the length of the preparation region is preferably set to a length that requires a passage time of 0.5 seconds or more and 1.0 seconds or less depending on the flow rate of the processing gas. The flow rate of the processing gas is preferably maintained at a certain level in order to avoid obstacles due to reaction products (reduction in reaction rate). For example, a flow rate of about 50 to 500 mm / s is adopted, so that the length of the preparation region is long. It can be said that the thickness is preferably about 25 to 500 mm.

Next, a second embodiment will be described.
FIG. 9 is a schematic configuration diagram illustrating an optical processing apparatus according to the second embodiment.
Since the optical processing apparatus 200 according to the second embodiment is the same as the embodiment shown in FIG. 1 except that the preparation method of the preparation area is different, the description thereof is omitted below.
In the second embodiment, a pin 21e is provided on the stage 21, and the placement of the substrate W from the pin 21e on the right side of the drawing is prohibited by the pin 21e. That is, the pin 21e forms a preparation area where the placement of the substrate W is prohibited. The pin 21e also corresponds to an example of a forming tool according to the present invention.
When the pins 21e are provided in this way, adjustment to adjust the width of the processing region to the size of the substrate W is easy.

Next, experimental examples conducted for confirming the effects of the present invention will be described.
(Experimental example)
With reference to the configuration shown in FIG. 1, an optical processing apparatus according to the present invention having the following specifications was produced.
[Stage 21]
Dimensions: 755 x 650mm, thickness 20mm
Material: Aluminum Preparation area length: 100mm
Heating temperature: 150 ° C
[Ultraviolet light source 11]
Xenon excimer lamp Light emission length: 700mm
Width: 70mm
Input power: 500W
Number of lamps: 7 Vacuum UV irradiation time: 300 seconds

[Window member 12]
Dimensions: 755 x 650mm, thickness 5mm
Material: Quartz glass Distance between window member and substrate: 0.3 mm
[Substrate W]
Configuration: Insulating layer laminated on a copper substrate, and via hole formed in the insulating layer Dimensions: 500 mm x 500 mm x 0.5 mm
Insulating layer thickness: 30 μm
Via hole diameter: 50 μm
[Conditions for processing gas, etc.]
Processing gas: oxygen concentration 100%
Processing gas flow rate: 1.0 L / min
In the optical processing apparatus having such a specification, it took about 0.9 seconds for the processing gas to pass through the preparation region, and processing unevenness in the substrate W did not occur.

In the above description, an application example to a desmear processing apparatus is shown as an example of the optical processing apparatus of the present invention. However, the optical processing apparatus of the present invention is, for example, an optical ashing processing apparatus, a resist removal processing apparatus, or a dry processing apparatus. You may apply to a washing | cleaning processing apparatus etc.
Moreover, in the said description, although the stage 21 provided with the formation tool said to this invention is illustrated, the mounting base and process part said to this invention may not have a formation tool.

  DESCRIPTION OF SYMBOLS 100 ... Optical processing apparatus, W ... Board | substrate, 10 ... Light irradiation part, 20 ... Processing part, 11 ... Ultraviolet light source, 12 ... Window member, 21 ... Stage, R1 ... Processing area | region, R2 ... Preparation area | region

Claims (4)

A light source that emits light;
A processing unit in which an object to be processed is exposed to light emitted from the light source unit,
The processing unit is
A processing region in which the object to be processed is held and exposed to the light in an atmosphere of a processing gas;
A preparation area in which the processing gas is exposed to the light and passes to the processing area, and the arrangement of the object to be processed is prohibited.
The flow rate of the processing gas is 50 to 500 mm / s,
The length of the said preparation area | region is 25-500 mm, The optical processing apparatus characterized by the above-mentioned . The processing unit is
A mounting table on which the object to be processed is mounted;
A forming tool that prevents the object to be processed from being placed on a part of the mounting table and forms the preparation area;
The optical processing apparatus according to claim 1, further comprising: The light source unit includes a window plate that transmits light;
The processing unit includes a mounting table on which the object to be processed is mounted facing the window plate,
The optical processing apparatus according to claim 1, wherein the preparation area is an area sandwiched between the window plate and a portion of the mounting table on which the object to be processed is not placed. A preparatory step of irradiating a process gas passing through a preparation region having a length of 25 to 500 mm at a flow rate of 50 to 500 mm / s with light emitted from a light source;
A treatment step of irradiating the object to be treated disposed in the atmosphere of the treatment gas in the treatment region following the preparation region with light emitted from the light source;
The light processing method characterized by passing through.

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