CN108456864B - Epitaxial layer growth equipment and defect detection method in epitaxial layer growth process - Google Patents

Epitaxial layer growth equipment and defect detection method in epitaxial layer growth process Download PDF

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CN108456864B
CN108456864B CN201711463957.XA CN201711463957A CN108456864B CN 108456864 B CN108456864 B CN 108456864B CN 201711463957 A CN201711463957 A CN 201711463957A CN 108456864 B CN108456864 B CN 108456864B
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epitaxial layer
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CN108456864A (en
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向光胜
叶青贤
喻海波
蔡云聪
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HC Semitek Zhejiang Co Ltd
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HC Semitek Zhejiang Co Ltd
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    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/52—Means for observation of the coating process
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C14/00—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material
    • C23C14/22—Coating by vacuum evaporation, by sputtering or by ion implantation of the coating forming material characterised by the process of coating
    • C23C14/54—Controlling or regulating the coating process
    • C23C14/542—Controlling the film thickness or evaporation rate
    • C23C14/545—Controlling the film thickness or evaporation rate using measurement on deposited material
    • C23C14/547—Controlling the film thickness or evaporation rate using measurement on deposited material using optical methods
    • C—CHEMISTRY; METALLURGY
    • C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
    • C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
    • C23C16/00—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes
    • C23C16/44—Chemical coating by decomposition of gaseous compounds, without leaving reaction products of surface material in the coating, i.e. chemical vapour deposition [CVD] processes characterised by the method of coating
    • C23C16/52—Controlling or regulating the coating process
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B23/00—Single-crystal growth by condensing evaporated or sublimed materials
    • C30B23/002—Controlling or regulating
    • C—CHEMISTRY; METALLURGY
    • C30—CRYSTAL GROWTH
    • C30B—SINGLE-CRYSTAL GROWTH; UNIDIRECTIONAL SOLIDIFICATION OF EUTECTIC MATERIAL OR UNIDIRECTIONAL DEMIXING OF EUTECTOID MATERIAL; REFINING BY ZONE-MELTING OF MATERIAL; PRODUCTION OF A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; SINGLE CRYSTALS OR HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; AFTER-TREATMENT OF SINGLE CRYSTALS OR A HOMOGENEOUS POLYCRYSTALLINE MATERIAL WITH DEFINED STRUCTURE; APPARATUS THEREFOR
    • C30B25/00—Single-crystal growth by chemical reaction of reactive gases, e.g. chemical vapour-deposition growth
    • C30B25/02—Epitaxial-layer growth
    • C30B25/16—Controlling or regulating

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Abstract

The invention discloses epitaxial layer growth equipment and a defect detection method in an epitaxial layer growth process, and belongs to the technical field of semiconductors. The growth equipment comprises a reaction chamber and a detection device, wherein the detection device comprises a light source module used for providing ultraviolet light irradiated on an epitaxial layer in growth; the image acquisition module is used for acquiring an image to be detected generated by ultraviolet light irradiating on the epitaxial layer when at least one growth stage is finished; the processing module is used for judging whether the epitaxial layer grows to the end of the growth stage according to the gray level of the image to be detected, irradiating the generated image to be detected on the epitaxial layer by ultraviolet rays in the current growth stage and judging whether the epitaxial layer has defects according to the gray level of the image to be detected, the defects formed in the growth process of the epitaxial layer can be fed back in time when the defects appear in the growth of the epitaxial layer, operators can adjust the growth of the epitaxial layer in time, the internal defects of the epitaxial layer are reduced, and the yield of the epitaxial wafer is improved.

Description

Epitaxial layer growth equipment and defect detection method in epitaxial layer growth process
Technical Field
The invention relates to the technical field of semiconductors, in particular to epitaxial layer growth equipment and a defect detection method in the epitaxial layer growth process.
Background
An LED (Light Emitting Diode) has the advantages of small size, long service life, low power consumption, and the like, and is currently widely used in automobile signal lamps, traffic signal lamps, display screens, and lighting devices. In the manufacturing process of the LED, the most important thing is the manufacture of the epitaxial wafer, the epitaxial wafer comprises a substrate and an epitaxial layer grown on the substrate, and the quality of the epitaxial layer has a great influence on the quality of the LED.
In order to improve the quality of the LED and reduce the defective products, the epitaxial layer is usually inspected after the epitaxial wafer is manufactured, or the single LED chip is inspected after the LED chip is manufactured to determine whether the epitaxial layer or each region on the LED chip has defects.
Because the existing epitaxial layer detection can only be carried out after the epitaxial layer is grown, and the defects in the epitaxial layer are already formed after the epitaxial layer is grown, the existing detection can only be used for conveniently removing the defective epitaxial wafer or LED chip, the defects in the epitaxial layer can not be reduced, and the yield of the epitaxial wafer is improved.
Disclosure of Invention
In order to reduce defects inside an epitaxial layer and improve the yield of epitaxial wafers, the embodiment of the invention provides a defect detection device and a defect detection method. The technical scheme is as follows:
in one aspect, an embodiment of the present invention provides an epitaxial layer growth apparatus, where the growth apparatus includes a reaction chamber, the growth apparatus further includes a detection device, the detection device is disposed in the reaction chamber, and the detection device includes:
the light source module is used for providing ultraviolet light irradiated on the growing epitaxial layer;
the image acquisition module is used for acquiring an image to be detected generated by the ultraviolet light irradiating on the epitaxial layer when at least one growth stage is finished;
and the processing module is used for judging whether the epitaxial layer grown to the end of the growth stage has defects or not according to the gray scale of the image to be detected.
Optionally, the processing module includes:
the device comprises a selecting unit, a judging unit and a judging unit, wherein the selecting unit is used for selecting a plurality of to-be-detected areas on the to-be-detected image, the plurality of to-be-detected areas are not overlapped with each other, the set of the plurality of to-be-detected areas covers the to-be-detected image, the shape and the area of the to-be-detected areas are the same as those of a standard image, and the standard image is an image of a defect-free epitaxial layer growing;
the acquiring unit is used for acquiring the gray value of each pixel of each region to be detected on the image to be detected;
and the comparison unit is used for comparing the gray value of each pixel of each region to be detected on the image to be detected with the gray value of each pixel of the standard image to determine whether the region on the epitaxial layer corresponding to each region to be detected has defects.
In particular, the comparison unit is configured to,
when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected exceeds a preset value, judging that the region on the epitaxial layer corresponding to the region to be detected has a defect;
and when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected does not exceed a preset value, judging that no defect exists in the region on the epitaxial layer corresponding to the region to be detected.
Specifically, the preset value is 1-3% of the number of pixels in the region to be detected.
Optionally, the image acquiring module is configured to acquire the to-be-measured image generated by the ultraviolet light irradiating on the epitaxial layer at the end of each growth phase.
Optionally, the light source module includes:
a light source for providing the ultraviolet light;
and the adjusting unit is used for adjusting the emergent intensity of the ultraviolet light.
On the other hand, the embodiment of the invention provides a defect detection method in an epitaxial layer growth process, which is characterized by comprising the following steps:
irradiating ultraviolet light on the growing epitaxial layer;
acquiring an image to be detected generated by the ultraviolet light irradiating on the epitaxial layer at the end of at least one growth stage;
and judging whether the epitaxial layer grown to the end of the growth stage has defects or not according to the gray scale of the image to be detected.
Optionally, the determining whether the epitaxial layer grown to the end of the growth stage has a defect according to the image to be detected includes:
selecting a plurality of regions to be detected on the image to be detected, wherein the regions to be detected are not overlapped with each other, the set of the regions to be detected covers the image to be detected, the shape and the area of the region to be detected are the same as those of a standard image, and the standard image is an image of a defect-free epitaxial layer grown to the end of the growth stage;
acquiring the gray value of each pixel of each region to be detected on the image to be detected;
and comparing the gray value of each pixel of each region to be detected on the image to be detected with the gray value of each pixel of the standard image to determine whether the region on the epitaxial layer corresponding to each region to be detected has defects.
Specifically, the comparing the gray value of each pixel of each region to be detected with the gray value of each pixel of the standard image to determine whether the region on the epitaxial layer corresponding to each region to be detected has a defect includes:
when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected exceeds a preset value, judging that the region on the epitaxial layer corresponding to the region to be detected has a defect;
and when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected does not exceed a preset value, judging that no defect exists in the region on the epitaxial layer corresponding to the region to be detected.
Optionally, the acquiring, at the end of at least one growth phase, an image to be measured generated by the ultraviolet light irradiating on the epitaxial layer includes:
and respectively acquiring an image to be detected generated by the ultraviolet light irradiating on the epitaxial layer at the end of each growth stage.
The technical scheme provided by the embodiment of the invention has the following beneficial effects: the epitaxial layer in the growth is irradiated through the ultraviolet ray, and acquire the image that awaits measuring that current growth stage ultraviolet irradiation produced on the epitaxial layer, judge whether there is the defect to the epitaxial layer of current stage of growing according to the grey scale of the image that awaits measuring again, thereby can be when the defect appears in epitaxial layer growth, in time feed back the defect that the epitaxial layer growth in-process formed, the operating personnel of being convenient for in time makes the adjustment to the growth of epitaxial layer, avoid follow-up growth in-process defect further to enlarge, be favorable to reducing the internal defect of epitaxial layer, improve the yield of epitaxial wafer.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.
Fig. 1 is a schematic partial structural view of an epitaxial wafer growth apparatus according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of a conventional epitaxial wafer;
FIG. 3 is a schematic structural diagram of a processing module according to an embodiment of the present invention;
FIG. 4 is a flowchart of a defect detection method in an epitaxial wafer growth process according to an embodiment of the present invention;
fig. 5 is a flowchart of another defect detection method in the epitaxial wafer growth process according to an embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
Fig. 1 is a schematic partial structural view of an epitaxial wafer growth apparatus according to an embodiment of the present invention, and as shown in fig. 1, the growth apparatus includes a reaction chamber and a detection device, and the detection device is disposed in the reaction chamber.
The detection device comprises a light source module 101, an image acquisition module 102 and a processing module 103.
The light source module 101 is used to provide ultraviolet light to the growing epitaxial wafer 200. The image obtaining module 102 is configured to obtain an image to be measured generated by irradiating ultraviolet light on an epitaxial layer of the epitaxial wafer 200 at the end of at least one growth phase. The processing module 103 is configured to determine whether the epitaxial layer grown to the end of the growth phase has a defect according to the gray scale of the image to be detected.
According to the embodiment of the invention, the epitaxial layer in growth is irradiated by ultraviolet rays, the image to be detected generated by irradiating the epitaxial layer by the ultraviolet rays in the current growth stage is obtained, and whether the defect exists in the epitaxial layer grown to the current stage is judged according to the gray level of the image to be detected, so that the defect formed in the epitaxial layer growth process can be fed back in time when the defect occurs in the epitaxial layer growth, an operator can adjust the growth of the epitaxial layer in time, the defect in the subsequent growth process is prevented from being further enlarged, the internal defect of the epitaxial layer is reduced, and the yield of the epitaxial wafer is improved.
Fig. 2 is a schematic structural diagram of a conventional epitaxial wafer, and in practical applications, an epitaxial wafer 200 may include a substrate 201 and an epitaxial layer formed on the substrate 201, where the epitaxial layer may include an N-type layer 202, an active layer 203, a P-type layer 204, a conductive layer 205, and a passivation protection layer 206 sequentially stacked on the substrate 201, and a defect 200a is located in the epitaxial layer. The structure of the epitaxial layer may also be different for different epitaxial wafers, for example, a distributed bragg mirror, a GaN buffer layer, etc. are also included in part of the epitaxial layer. The growth process of the epitaxial layers includes a number of different growth stages, each growth stage growing a different layer structure, including, for example, a growth stage for growing N-type layer 202, a growth stage for growing active layer 203, a growth stage for growing P-type layer 204, and the like.
Optionally, the image acquiring module 102 may be configured to acquire the images to be measured generated by irradiating the epitaxial layer with the ultraviolet light at the end of each growth phase.
For example, after the N-type layer 202 is grown, an image to be detected is obtained once, and a detection is performed once to detect whether a defect exists in the epitaxial layer after the N-type layer 202 is grown. And acquiring an image to be detected again after the active layer 203 is grown, and detecting again to detect whether defects exist in the epitaxial layer after the active layer 203 is grown. The image to be detected is obtained once through each growth layer, and the detection is carried out once, so that whether defects exist in the epitaxial layer or not can be detected, whether defects exist in each layer or not can also be detected, the growth condition can be conveniently adjusted by an operator to reduce the defects in subsequent growth, the defects formed in the epitaxial layer are favorably reduced, the quality of the finally formed epitaxial layer is improved, and the yield of the epitaxial wafer is improved.
Referring to fig. 1, the light source module 101 and the image obtaining module 102 may be located on the same side of the growing epitaxial wafer 200, and the image obtaining module 102 may be located on a side of the light source module 101 away from the epitaxial wafer 200, where the light source module 101 irradiates the surface of the epitaxial wafer 200 with ultraviolet light, and the image obtaining module 102 receives the ultraviolet light reflected by the epitaxial wafer 200 to obtain an image to be measured corresponding to the current growth stage. Because the epitaxial layer comprises a stacked multilayer structure, ultraviolet light can be reflected at the interface of two adjacent layers while penetrating through the epitaxial layer, the stronger the light transmittance of the epitaxial layer is, the weaker the reflected light is, and the stronger the transmitted light is, whereas the weaker the light transmittance is, the stronger the reflected light is, and the weaker the transmitted light is, the reflected ultraviolet light can be received by the image acquisition module 102, and the image to be measured is formed. In the epitaxial layer, the defective region and the non-defective region have different transmittances, which causes the intensity of the ultraviolet light reflected by the defective region to be different from that of the non-defective region, and the intensity of the ultraviolet light reflected by the defective region is specifically represented on an image, and the defective region and the non-defective region are different in brightness.
The processing module 103 may be electrically connected to the image acquisition module 102.
Alternatively, the light source module 101 may include a light source 1011 and an adjusting unit 1012, wherein the light source 1011 is used for providing ultraviolet light, and the adjusting unit 1012 is used for adjusting the emergent intensity of the ultraviolet light. So that the image acquisition module 102 can acquire a stable and clear image to be detected, and specifically, the power of the light source 1011 can be adjusted to increase or decrease the emergent intensity of ultraviolet light, so that different light and shade regions can be clearly distinguished on the formed image to be detected.
Preferably, the light source 1011 can be an ultraviolet LED, which has the advantages of long service life and low energy consumption, and is beneficial to reducing the cost. In practice, the light source may emit light having a wavelength of 260nm to 420 nm.
As shown in fig. 1, the light source module 101 may include two light sources 1011, the two light sources 1011 are spaced apart, the two light sources 1011 simultaneously emit ultraviolet light to the epitaxial wafer 200, and the reflected ultraviolet light passes through the space between the two light sources 1011 and is acquired by the image acquisition module 102.
Alternatively, the image acquisition module 102 may be a photoelectric sensor, and specifically may be a CCD (Charge-coupled Device) or a CMOS (Complementary Metal oxide semiconductor).
Fig. 3 is a schematic structural diagram of a processing module according to an embodiment of the present invention, as shown in fig. 3, the processing module 103 may include a selection unit 1031, an obtaining unit 1032, and a comparison unit 1033, where the selection unit 1031 is configured to select a plurality of regions to be measured on an image to be measured, the plurality of regions to be measured are not overlapped with each other, a set of the plurality of regions to be measured covers the entire image to be measured, a shape and an area of the region to be measured are the same as those of a standard image, and the standard image is an image of an epitaxial layer that grows to a current growth stage without defects. The obtaining unit 1032 is configured to obtain a gray value of each pixel of each region to be measured on the image to be measured. The comparing unit 1033 is configured to compare the gray level values of the pixels of each to-be-measured region on the to-be-measured image with the gray level values of the pixels of the standard image, and determine whether the region on the epitaxial layer corresponding to each to-be-measured region has a defect.
Wherein, the range of the gray value is 0-255. The larger the gray scale value of the pixel is, the higher the brightness of the pixel is, the stronger the ultraviolet light reflected by the region corresponding to the pixel is, i.e. the poorer the light transmittance of the region corresponding to the pixel is. The larger the gray value of the pixel is, the poorer the light transmittance of the region corresponding to the pixel is, and the more serious the region defect on the epitaxial layer corresponding to the region to be measured where the pixel is located is. Conversely, the smaller the gray value of the pixel is, the better the light transmittance of the region corresponding to the pixel is, and the less the region defect on the epitaxial wafer corresponding to the region to be measured where the pixel is located is.
It should be noted that each growth stage has a corresponding standard image, so that it is possible to accurately detect whether there is a defect.
In practical application, the standard image of each growth stage may be manually selected from the images acquired by the image acquisition module, specifically, one block may be respectively selected from the images of each growth stage acquired by the image acquisition module to serve as the standard image of the corresponding growth stage, and the image of the area to be measured of a certain growth stage is compared with the standard image of the corresponding growth stage. It may also be preset, for example, by a test mode, to obtain images of a qualified epitaxial layer at each growth stage, and with these images as samples, select multiple areas from the samples as standard images corresponding to the growth stages, and when comparing an area to be measured on an image to be measured at a certain growth stage with the standard images corresponding to the growth stages, select the same area on the image to be measured as the area to be measured. In addition, only one area on the sample can be selected as a standard image of the corresponding growth stage, and any area to be detected on the image to be detected is compared with the same area on the sample.
Specifically, the selecting unit may include a selecting frame, and when selecting, the selecting frame may be placed on the image to be detected, and a plurality of different regions in the image to be detected are respectively selected to obtain a plurality of regions to be detected, where there is no overlapping portion between the plurality of regions to be detected.
Specifically, the comparing unit 1033 may be configured to determine that there is a defect in the region on the epitaxial layer corresponding to the region to be measured when the number of pixels in the region to be measured whose grayscale values are higher than the grayscale values of the pixels in the standard image exceeds a predetermined value; and when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected does not exceed a preset value, judging that no defect exists in the region on the epitaxial layer corresponding to the region to be detected. As the epitaxial layer inevitably generates certain defects in the growth process, the defects cannot be completely absent, the quality of the epitaxial layer can meet the production requirement as long as the number of the defects is controlled within a preset value, and therefore, when the defects in the area to be detected are controlled within the preset value, the area to be detected can be considered to be absent of the defects.
Preferably, the predetermined value may be 1 to 3% of the number of pixels in the region to be measured, and setting the predetermined value to 1 to 3% may make the manufactured epitaxial wafer meet most of the production requirements, and it is easily conceivable that the predetermined value may be set differently for different production requirements, and may be set to 1% or less, for example, 0.6%, when the quality requirement for the epitaxial wafer in production is high, and may be set to 3% or more, for example, 3.5%, when the quality requirement for the epitaxial wafer in production is low.
Fig. 4 is a flowchart of a defect detection method in an epitaxial layer growth process, where the defect detection method is applicable to the epitaxial layer growth apparatus shown in fig. 1, and as shown in fig. 4, the defect detection method includes:
s11: ultraviolet light is irradiated onto the growing epitaxial layer.
In this case, step S11 may be performed by the light source module.
S12: and acquiring an image to be measured generated by irradiating ultraviolet light on the epitaxial layer at the end of at least one growth stage.
In practice, step S12 may be performed by the aforementioned image acquisition module.
S13: and judging whether the epitaxial layer grown to the end of the growth stage has defects or not according to the gray scale of the image to be detected.
In practice, step S13 may be performed by the aforementioned processing module.
According to the embodiment of the invention, the epitaxial layer in growth is irradiated by ultraviolet rays, the image to be detected generated by irradiating the epitaxial layer by the ultraviolet rays in the current growth stage is obtained, and whether the defect exists in the epitaxial layer grown to the current stage is judged according to the gray level of the image to be detected, so that the defect formed in the epitaxial layer growth process can be fed back in time when the defect occurs in the epitaxial layer growth, an operator can adjust the growth of the epitaxial layer in time, the defect in the subsequent growth process is prevented from being further enlarged, the internal defect of the epitaxial layer is reduced, and the yield of the epitaxial wafer is improved.
In addition, the bright spots in the image to be detected can be observed by naked eyes, and the number of the bright spots shows the number of the defects.
Fig. 5 is a flowchart of another defect detection method in an epitaxial layer growth process, where the defect detection method is applicable to the epitaxial layer growth apparatus shown in fig. 1, and as shown in fig. 5, the defect detection method includes:
s21: ultraviolet light is irradiated onto the growing epitaxial layer.
In this case, step S21 may be performed by the light source module.
S22: and acquiring an image to be measured generated by irradiating ultraviolet light on the epitaxial layer at the end of at least one growth stage.
In practice, step S22 may be performed by the aforementioned image acquisition module.
S23: and selecting a plurality of regions to be detected on the image to be detected.
The plurality of regions to be measured are not overlapped with each other, the set of the plurality of regions to be measured covers the image to be measured, the shape and the area of the region to be measured are the same as those of the standard image, and the standard image is an image of the epitaxial layer which grows to be free of defects in the current growth stage.
In this case, step S23 may be performed by the aforementioned selecting unit.
The number of the selected areas to be detected is different according to different quality requirements, and the more the number of the selected areas to be detected is, the more accurate the detection result is, but correspondingly, the more the cost is invested in the detection.
S24: and acquiring the gray value of each pixel of each region to be detected on the image to be detected.
In implementation, step S24 may be performed by the aforementioned acquisition unit.
S25: and judging whether the area on the epitaxial layer corresponding to each area to be detected on the image to be detected has defects or not.
In implementation, step S25 may be performed by the aforementioned comparing unit.
Specifically, when the number of pixels in the region to be detected, the gray value of which is higher than the gray value of the pixels of the standard image, exceeds a predetermined value, it is determined that the region on the epitaxial layer corresponding to the region to be detected has a defect.
And when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected does not exceed a preset value, judging that no defect exists in the region on the epitaxial layer corresponding to the region to be detected.
Preferably, the predetermined value may be 1 to 3% of the number of pixels in the region to be measured, and setting the predetermined value to 1 to 3% may make the manufactured epitaxial wafer meet most of the production requirements, and it is easily conceivable that the predetermined value may be set differently for different production requirements, and may be set to 1% or less, for example, 0.6%, when the quality requirement for the epitaxial wafer in production is high, and may be set to 1% or more, for example, 1.5%, when the quality requirement for the epitaxial wafer in production is low.
Further, step S22 may include:
and respectively acquiring an image to be detected generated by irradiating the epitaxial layer with ultraviolet light at the end of each growth stage.
Therefore, the images to be detected at the end of a plurality of different growth stages can be obtained, the detection is carried out once when the images to be detected are obtained, and the subsequent growth environment is adjusted according to the detection result, so that the quality of the epitaxial layer is further improved, and the yield of the epitaxial wafer is improved.
It should be noted that: in the growth apparatus for an epitaxial wafer according to the above embodiment, when defect detection is performed in the growth process of the epitaxial wafer, only the division of the functional modules is illustrated, and in practical applications, the function distribution may be completed by different functional modules according to needs, that is, the internal structure of the apparatus may be divided into different functional modules to complete all or part of the functions described above. In addition, the growth device for the epitaxial wafer provided by the above embodiment and the defect detection method in the growth process of the epitaxial wafer belong to the same concept, and specific implementation processes thereof are detailed in the method embodiments and are not described herein again.
It will be understood by those skilled in the art that all or part of the steps for implementing the above embodiments may be implemented by hardware, or may be implemented by a program instructing relevant hardware, where the program may be stored in a computer-readable storage medium, and the above-mentioned storage medium may be a read-only memory, a magnetic disk or an optical disk, etc.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents, improvements and the like that fall within the spirit and principle of the present invention are intended to be included therein.

Claims (4)

1. The growth equipment of epitaxial layer, growth equipment includes reaction chamber, its characterized in that, growth equipment still includes detection device, detection device sets up in reaction chamber, detection device includes:
the light source module is used for providing ultraviolet light irradiated on the growing epitaxial layer;
the image acquisition module is used for acquiring the ultraviolet light reflected by the epitaxial layer so as to respectively acquire an image to be detected generated by the ultraviolet light irradiating on the epitaxial layer when each growth stage is finished;
a processing module, configured to determine whether the epitaxial layer grown to the end of the growth phase has a defect according to the gray level of the image to be detected, where the processing module includes:
the device comprises a selecting unit, a judging unit and a judging unit, wherein the selecting unit is used for selecting a plurality of to-be-detected areas on the to-be-detected image, the plurality of to-be-detected areas are not overlapped with each other, the set of the plurality of to-be-detected areas covers the to-be-detected image, the shape and the area of the to-be-detected areas are the same as those of a standard image, and the standard image is an image of a defect-free epitaxial layer growing;
the acquiring unit is used for acquiring the gray value of each pixel of each region to be detected on the image to be detected;
the comparison unit is used for comparing the gray value of each pixel of each to-be-detected area on the to-be-detected image with the gray value of each pixel of the standard image, determining whether the area on the epitaxial layer corresponding to each to-be-detected area has defects, and judging that the area on the epitaxial layer corresponding to the to-be-detected area has defects when the number of pixels, of which the gray values are higher than the gray values of the pixels of the standard image, in the to-be-detected area exceeds a preset value; and when the number of pixels with the gray values higher than the gray values of the pixels of the standard image in the region to be detected does not exceed a preset value, judging that no defect exists in the region on the epitaxial layer corresponding to the region to be detected.
2. The growing apparatus according to claim 1, wherein the predetermined value is 1-3% of the number of pixels in the area under test.
3. The growing apparatus of claim 1 or 2, wherein the light source module comprises:
a light source for providing the ultraviolet light;
and the adjusting unit is used for adjusting the emergent intensity of the ultraviolet light.
4. A defect detection method in the epitaxial layer growth process is characterized by comprising the following steps:
irradiating ultraviolet light on the growing epitaxial layer;
acquiring the ultraviolet light reflected by the epitaxial layer so as to respectively acquire an image to be detected generated by the ultraviolet light irradiating on the epitaxial layer at the end of each growth stage;
judging whether the epitaxial layer grown to the end of the growth stage has defects or not according to the gray scale of the image to be detected,
the judging whether the epitaxial layer grown to the end of the growth stage has defects according to the image to be detected comprises the following steps:
selecting a plurality of regions to be detected on the image to be detected, wherein the regions to be detected are not overlapped with each other, the set of the regions to be detected covers the image to be detected, the shape and the area of the region to be detected are the same as those of a standard image, and the standard image is an image of a defect-free epitaxial layer grown to the end of the growth stage;
acquiring the gray value of each pixel of each region to be detected on the image to be detected;
comparing the gray value of each pixel of each to-be-detected area on the to-be-detected image with the gray value of each pixel of the standard image, determining whether the area on the epitaxial layer corresponding to each to-be-detected area has defects, when the number of pixels with the gray values higher than the gray value of the pixels of the standard image in the to-be-detected area exceeds a preset value, determining that the area on the epitaxial layer corresponding to the to-be-detected area has defects, and when the number of pixels with the gray values higher than the gray value of the pixels of the standard image in the to-be-detected area does not exceed the preset value, determining that the area on the epitaxial layer corresponding to the to-be-detected area has no defects.
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