WO2017206772A1

WO2017206772A1 - Light emitting diode with electrostatic protection function and manufacturing method therefor

Info

Publication number: WO2017206772A1
Application number: PCT/CN2017/085659
Authority: WO
Inventors: 吴超瑜; 吴俊毅; 王笃祥
Original assignee: 厦门三安光电有限公司
Priority date: 2016-06-01
Filing date: 2017-05-24
Publication date: 2017-12-07
Also published as: CN106025017A; CN106025017B

Abstract

A light emitting diode with an electrostatic protection function and a manufacturing method therefor. An electrostatic protection region, an electrode region and a light emission region are arranged on a light emission surface of a chip. A first N-type ohmic contact electrode (141) is formed on the electrode region. An antistatic protection structure composed of an etching stop layer (116), tunnel junctions (114, 115), electrostatic protection layers (112, 113) and a second N-type ohmic contact electrode (142) is formed in the electrostatic protection region. When the light emitting diode is subjected to an electrostatic reverse biased voltage, the antistatic protection structure works. The current passes through the first N-type ohmic contact electrode (141) and the electrostatic protection structure to the second N-type ohmic contact electrode (142), so that the damage of the light emitting layer caused by an overhigh electrostatic reverse biased voltage can be avoided.

Description

Light-emitting diode with electrostatic protection and manufacturing method thereof

[0001] The present invention relates to the field of semiconductor illumination, and more particularly to a light-emitting diode having an antistatic protection structure and a method of fabricating the same.

Background technique

[0002] A light emitting diode is a semiconductor solid state light emitting device that utilizes a semiconductor PN junction as a light emitting material to directly convert electricity into light. The forward and reverse current or voltage of the LED must pass through the illuminating layer. If the reverse voltage is applied too much, the chip may be broken down, causing the chip to fail.

[0003] Chinese Patent Publication No. CN102308397A discloses a light-emitting diode and a light-emitting diode lamp, which is provided with a third electrode at the bottom of the transparent substrate, and is configured to pass the n-type ohmic electrode and the third electrode through the assembly of the light-emitting diode lamp. The n-electrode terminal is electrically connected to be equipotential or substantially equipotential, and the breakdown voltage from the transparent substrate side to the P-type GaP layer side is lower than the reverse voltage of the PN junction-type light-emitting portion. Therefore, instead of causing a reverse current generated by inadvertently applying a reverse voltage 经由 to flow through the n-type ohmic electrode provided above the light-emitting portion to the light-emitting portion having a high reverse voltage of the PN junction portion, it is not preferable to pass the The third electrode flows through the junction region of the transparent group having a low breakdown voltage and the p-type GaP layer, and can escape to the P-type ohmic electrode without passing through the light-emitting portion. Therefore, it is possible to avoid the destruction of the light-emitting portion of the light-emitting diode caused by the careless flow of the reverse overcurrent.

[0004] However, the structure for preventing reverse voltage breakdown of the light-emitting diodes must be a chip structure on the same side of the horizontal plate PN electrode, which is not suitable for the vertical plate, which greatly reduces the number of technical problems of the LED application.

Problem solution

Technical solution

In view of the foregoing problems, the present invention provides an LED structure having electrostatic protection, which prevents reverse voltage breakdown structures from being formed on LED chips, thereby increasing chip quality and ease of use.

[0006] The technical solution of the present invention to solve the above problems is as follows: an epitaxial wafer of a light-emitting diode with electrostatic protection And comprising: a growth substrate; an electrostatic protection layer composed of an N-type semiconductor layer and a P-type semiconductor layer, formed on the growth substrate; a tunneling junction formed on the electrostatic protection layer; An etch-off layer is formed over the tunneling junction; an N-type cladding layer is formed over the second etch-off layer; a luminescent layer is formed over the N-type cladding layer; and a P-type cladding layer, Formed on the luminescent layer.

[0007] The LED chip structure adopting the above epitaxial structure comprises: a light emitting portion, comprising a P-type cover layer, a light-emitting layer and an N-type cover layer, wherein an upper surface thereof is divided into an exit region, an electrode region and an electrostatic protection region; and antistatic protection The structure is disposed on the electrostatic protection region of the light-emitting portion, and includes an etch-off layer, a tunnel junction, and an electrostatic protection layer, wherein the electrostatic protection layer is composed of an N-type semiconductor layer and a P-type semiconductor layer; a type ohmic contact electrode formed on the electrode region of the light emitting portion; a second N-type ohmic contact electrode formed on the electrostatic protection layer; and the antistatic protection when the light emitting diode is subjected to electrostatic reverse bias The structure works, the current passes through the first N-type ohmic contact electrode, the electrostatic protection structure to the second N-type ohmic contact electrode, and the electrostatic reverse bias is prevented from being excessively caused to cause the luminescent layer to be destroyed. As a preferred embodiment of the present invention, the light-emitting portion is bonded to the conductive substrate through the metal bonding layer. More preferably, a mirror structure may be provided between the light-emitting portion and the metal bonding layer.

[0008] The method for fabricating the above-mentioned electrostatic protection LED chip comprises the following steps: 1) epitaxial growth: epitaxial growth on a growth substrate to form an epitaxial wafer, which comprises from bottom to top: a growth substrate, an N-type semiconductor An electrostatic protection layer composed of a layer and a P-type semiconductor layer, a tunneling junction, an etch-off layer, an N-type cladding layer, a light-emitting layer, and a P-type cladding layer; 2) a transfer growth substrate: providing a conductive substrate through a metal bond Bonding the surface to the surface of the P-type cover layer of the epitaxial wafer, removing the growth substrate to expose the surface of the epitaxial wafer; 3) fabricating an antistatic protection structure: defining light on the surface of the exposed epitaxial wafer a region, an electrode region, and an electrostatic protection region, removing an electrostatic protection layer, a tunneling junction, and an etch-off layer of the light-emitting region and the electrode region; 4) fabricating an electrode: forming a first N-type ohm in an electrode region on a surface of the epitaxial wafer A second N-type ohmic contact electrode is formed on the electrostatic protection layer by a contact electrode. In the LED structure formed above, the etch stop layer, the tunnel junction, the electrostatic protection layer and the second N-type ohmic contact electrode constitute an antistatic protection structure, and when the LED is subjected to electrostatic reverse bias, the antistatic The protection structure works, and the current flows through the first N-type ohmic contact electrode and the electrostatic protection structure to the second N-type ohmic contact electrode to prevent the luminescent layer from being damaged due to excessive electrostatic reverse bias.

[0009] Preferably, the N-type semiconductor layer constituting the electrostatic protection layer is the same as the N-type ohmic contact semiconductor layer [0010] Preferably, the electrostatic protection layer is composed of an N-GaAs layer and a P-GaAs layer.

[0011] Preferably, the tunneling junction is composed of a P-type heavily miscellaneous layer and an N-type heavily miscellaneous layer, wherein the P-grain miscellaneous layer is P+ +-GaAs, and the impurity concentration is ≥1E19, and the N is heavy. The layer is N++-GaAs, and its impurity concentration is ≥1E20.

[0012] Preferably, the etch-off layer is N-type miscellaneous, the impurity concentration is at least 1E18 or more, preferably 5E 18, and the miscellaneous material may be Si, Te, and the thickness is at least 1000 or more, and the material may be InGaP, GaP, GaAs, AlInP, AlAs or AlGaAs is used.

[0013] Preferably, an N-type ohmic contact semiconductor layer is further disposed between the etch stop layer and the N-type cap layer

[0014] Preferably, an N-type current transport layer is further disposed between the N-type ohmic contact semiconductor layer and the N-type cap layer, and the impurity concentration is ≥5E17, and the thickness is ≥2000 nm.

[0015] Preferably, the area of the light exit area is larger than the area of the electrostatic protection area.

Other features and advantages of the invention will be set forth in the description which follows, The objectives and other advantages of the invention will be realized and attained by the <RTI

Advantageous effects of the invention

Brief description of the drawing

DRAWINGS

The drawings are intended to provide a further understanding of the invention, and are intended to be a part of the description of the invention. In addition, the drawing figures are a summary of the description and are not drawn to scale.

1 is a side cross-sectional view of an LED epitaxial structure with electrostatic protection in accordance with an embodiment of the present invention.

2 is a side cross-sectional view showing the structure of an LED chip fabricated using the epitaxial structure shown in FIG. 1.

3 is a schematic diagram showing current flow in a normal operation mode of an LED chip with electrostatic protection according to an embodiment of the present invention.

4 is a schematic diagram showing current flow in an antistatic operation mode of an LED chip with electrostatic protection according to an embodiment of the present invention.

[0022] FIG. 5 is a cross-sectional view of a process for fabricating an LED with electrostatic protection in accordance with an embodiment of the present invention. Embodiments of the invention

The embodiments of the present invention will be described in detail below with reference to the accompanying drawings and embodiments, in which the technical solutions of the present invention can be used to solve the technical problems, and the implementation of the technical effects can be fully understood and implemented. It should be noted that the various embodiments of the present invention and the various features of the various embodiments may be combined with each other as long as they do not constitute a conflict, and the technical solutions formed are all within the protection scope of the present invention.

Referring to FIG. 1, an epitaxial structure of an LED according to an embodiment of the present invention includes: a growth substrate 100, a first etch-off layer 111, an N-type layer 112 of an electrostatic protection layer, and an electrostatic protection layer P. The pattern layer 113, the P-type sever layer 114, the N-type sever layer 115, the second etch-off layer 116, the N-type ohmic contact layer 117, the N-type current diffusion layer 118, the N-type cladding layer 119, and the multiple quantum well light-emitting layer 120, P-type cap layer 121, P-type current diffusion layer 122 and P-type ohmic contact layer 123.

[0025] Specifically, the growth substrate 100 is made of a GaAs material; the first etch-off layer 111 is made of an N-InGaP material; and the N-type layer 112 of the electrostatic protection layer is made of an N-GaAs material, which can be used as an antistatic protection structure. The ohmic contact semiconductor layer; the P-type layer 113 of the electrostatic protection layer adopts a P-GaAs material; the P-type sever layer 114 and the N-type sever layer 115 constitute a tunnel junction, wherein the P-gravity layer 114 is P++-GaAs, The impurity concentration ≥1E19, N heavy miscellaneous layer 115 is N++-GaAs, and its impurity concentration is ≥1E20; the second etch-off layer 116 is N-type miscellaneous, and the impurity concentration is at least 1E18 or more, preferably 5E18. The material may be Si, Te, and the thickness is at least 1000A or more, and the material may be selected from InGaP, GaP, GaAs, AlInP, AlAs or AlGaAs; the material of the N-type ohmic contact layer 117 is GaAs; and the N-type current diffusion layer 118 is n- AlGaInP, the impurity concentration is at least 7E17 or more, preferably 1E18, the miscellaneous material may be Si, Te, the thickness is at least 1 micron or more, preferably 3 micrometers; the n-type cladding layer 119 is made of AllnP; Source layer 120 is a multiple quantum well structure The material of the p-type cladding layer 121 may be AllnP; the thickness of the p-type current diffusion layer 122 is 0.5-2 micrometers, preferably 1 micrometer; the material of the p-type ohmic contact layer 123 is p-GaP, and the impurity concentration is at least 8E17 or more, preferably 1E18, the miscellaneous material may be Mg, Zn, C, and has a thickness of at least 5 μm or more, preferably 10 μm.

The following table lists the main materials of the layers in the above-mentioned LED epitaxial structure and their related parameters.

[] [Table 1] Label Functional Material Thickness (nm) Miscellaneous Concentration

111 First Etch Cutoff InGaP: Si 100 5E18

Floor

112 Electrostatic protective layer GaAs: Si 100 1E18

N-type layer with N ohms

Contact semiconductor layer 1

113 Electrostatic protective layer P GaAs: C 100 3E18

Type layer

114 P heavy miscellaneous tunneling junction GaAs: C <20 >5E19

Floor

115 N heavy miscellaneous tunneling GaAs: Te <20 >5E19

Layer

116 Second Etch Cutoff InGaP: Si 200 5E18

Floor

117 N ohmic contact layer 2 GaAs: Si 60 1E18

118 N-type current diffusion AlGaInP: Si 3000 8E17

Floor

119 N-type overlay AlInP: Si 500 8E17

120 light layer AlGalnP 11*18 pair -

121 P-type overlay AlInP: Mg 900 1E18

122 P type current diffusion layer AlGaInP: Mg 25 2E18

123 P ohmic contact layer GaP: Mg 1200 3E18 2 shows a chip structure of a light emitting diode designed by using the above epitaxial structure, which includes, in order from bottom to top, a P electrode 143, a conductive substrate 101, a metal bonding layer 132, a mirror layer 131, and a P-type ohmic contact. Layer 123, P-type current diffusion layer 122, P-type cladding layer 121, light-emitting layer 120, N-type cladding layer 119, N-type current diffusion layer 118, N-type ohmic contact layer 117, second etch-off layer 116, N heavy The heterotunic tunneling layer 115, the P heavily doped tunneling layer 114, the P-type layer 113 of the electrostatic protection layer, the N-type layer of the electrostatic protection layer, the first ohmic contact electrode 141 and the second ohmic contact electrode 142. The upper surface of the N-type current diffusion layer 118 is divided into an exit region, an electrode region, and an electrostatic protection region. The N-type ohmic contact layer 117 is formed in the light exit region and the electrode region, and the second etch stop layer 116 and the N heavily miscellaneous tunneling The junction layer 115, the P heavily doped tunneling layer 114, the P-type layer 113 of the electrostatic protection layer, and the N-type layer 112 of the electrostatic protection layer are formed in the electrostatic protection region, and the first ohmic contact electrode 141 is formed in the N-type of the electrode region. On the ohmic contact layer 117, a second ohmic contact electrode 142 is formed on the N-type layer 112 of the electrostatic protection layer.

[0028] In the above LED chip structure, the N-type current diffusion layer 118, the second etch-off layer 116, the N-heavy tunneling layer 115, the P-heavy tunneling layer 114, and the P-type of the electrostatic protection layer The layer 113 and the N-type layer 112 of the electrostatic protection layer constitute an electrostatic protection structure. The LED chip of FIG. 2 is mounted on the PCB board 200吋, wherein the first N-type ohmic contact electrode 141 is connected to the negative electrode contact 200a of the PCB board 200, and the second N-type ohmic contact electrode 1 42 and the P electrode 143 and the PCB board 200 are connected. The positive electrode contact 200b is connected. When the light emitting diode is forward biased, the current flows through the P electrode 143 to the epitaxial light emitting layer to the first N-type ohmic contact electrode 141, and the chip works normally, as shown in FIG. 3; Under the reverse bias of the static electricity, the antistatic protection structure of the chip works, and the current passes through the first N-type ohmic contact electrode 141 to the electrostatic protection structure to the second N-type ohmic contact electrode 14 2, thereby avoiding the electrostatic reverse bias and causing the MQW light-emitting layer. Damaged, causing LED failure.

[0029] The following describes a method for fabricating the above light emitting diode.

[0030] First, the epitaxial structure shown in FIG. 1 is formed by an epitaxial growth method.

[0031] Next, substrate transfer is performed: a mirror layer 131 is formed on the surface of the p-type ohmic contact layer 123, which includes a P-type ohmic contact metal layer 131a and a highly transparent dielectric material layer 131b, which are provided on the one hand a P-type ohmic contact layer, on the other hand, for reflecting the light emitted downward by the light-emitting layer; providing a conductive substrate 101, coating a metal bonding layer 132 thereon, bonding the conductive substrate 101 and the mirror layer 131, and removing The substrate 100 is grown, and the N-type ohmic contact layer 112 is exposed, as shown in FIG.

[0032] Next, an antistatic protection structure is fabricated: light is defined on the surface of the exposed N-type ohmic contact layer 112. The region, the electrode region and the electrostatic protection region are fabricated by a yellow light chemical technique, and the N-type layer 112 of the electrostatic protection layer of the light-emitting region is removed by etching, the P-type layer 113 of the electrostatic protection layer, the P-type heavy layer 114, and the N-type heavy The layer 115, the second etch stop layer 116, the N-type ohmic contact layer 117, and the N-type layer 112 of the electrostatic protection layer of the electrode region, the P-type layer 113 of the electrostatic protection layer, the P-type heavy layer 114, and the N-type heavy layer 115, the second etch-off layer 116, thereby forming an N-type current diffusion layer 118, a second etch-off layer 116, an N-heavy tunneling layer 115, a P-heavy tunneling layer 114, and an electrostatic protection layer The P-type layer 113 and the N-type layer 112 of the electrostatic protection layer constitute an electrostatic protection structure.

[0033] Finally, an N-type ohmic contact electrode is fabricated: a first N-type ohmic contact electrode 141 is formed on the N-type ohmic contact layer 117 of the electrode region, and a second N-type ohmic contact is formed on the electrostatic protection layer 112 of the electrostatic protection region. The electrode 142 forms a light emitting diode having an antistatic protection structure.

[0034] It is to be understood that the description of the present invention should not be construed as being limited to the above-described embodiments, but rather to all possible embodiments that utilize the inventive concepts.

Claims

claims

[Claim 1] A light-emitting diode epitaxial wafer with electrostatic protection, including in order: a growth substrate; an electrostatic protection layer composed of an N-type semiconductor layer and a P-type semiconductor layer, formed on the growth substrate; tunnel A tie-through junction is formed on the electrostatic protective layer; an etching cutoff layer is formed on the tunnel junction; an N-type covering layer is formed on the second etching cutoff layer; a light-emitting layer is formed on the tunnel junction On the N-type cladding layer; P-type cladding layer, formed on the light-emitting layer

[Claim 2] The light-emitting diode epitaxial wafer with electrostatic protection according to claim 1, characterized in that: the N-type semiconductor layer constituting the electrostatic protection layer also serves as an N-type ohmic contact semiconductor layer.

[Claim 3] The light-emitting diode epitaxial wafer with electrostatic protection according to claim 1, characterized in that: the electrostatic protection layer is composed of an N-GaAs layer and a P-GaAs layer.

[Claim 4] The light-emitting diode epitaxial wafer with electrostatic protection according to claim 1, characterized in that: the tunnel junction is composed of a P-type heavy impurity layer and an N-type heavy impurity layer, wherein the P-type heavy impurity layer The impurity layer is P++-GaAs, and its impurity concentration is ≥1E19. The N-heavy impurity layer is N++-GaAs, and its impurity concentration is ≥1E20.

[Claim 5] The light-emitting diode epitaxial wafer with electrostatic protection according to claim 1, characterized in that: the thickness of the etching cutoff layer is ≥ 1000 Å.

[Claim 6] The light-emitting diode epitaxial wafer with electrostatic protection according to claim 1, characterized in that: an N-type ohmic contact semiconductor layer is further provided between the etching stop layer and the N-type cladding layer.

[Claim 7] The light-emitting diode epitaxial wafer with electrostatic protection according to claim 6, characterized in that: an N-type current transmission layer is further provided between the N-type ohmic contact semiconductor layer and the N-type cladding layer, Its impurity concentration ≥5E17, thickness ≥2000nm.

[Claim 8] A light-emitting diode chip with electrostatic protection, including:

The light-emitting part includes a P-type covering layer, a luminescent layer and an N-type covering layer, and its upper surface is divided into a light-emitting area, an electrode area and an electrostatic protection zone;

Antistatic protection structure, located above the electrostatic protection zone of the light-emitting part, including etching in turn Cut-off layer, tunnel junction, electrostatic protection layer, the electrostatic protection layer is composed of an N-type semiconductor layer and a p-type semiconductor layer; the first N-type ohmic contact electrode is formed on the electrode area of the light-emitting part; A second N-type ohmic contact electrode is formed on the electrostatic protective layer;

When the light-emitting diode is subjected to electrostatic reverse bias, the anti-static protection structure works, and the current passes through the first N-type ohmic contact electrode and the electrostatic protection structure to the second N-type ohmic contact electrode.

, to avoid damage to the light-emitting layer caused by excessive electrostatic reverse bias voltage.

The light-emitting diode chip with electrostatic protection according to claim 8, characterized in that

: The N-type semiconductor layer constituting the electrostatic protection layer also serves as the N-type ohmic contact semiconductor layer.

: The electrostatic protection layer is composed of an N-GaAs layer and a P-GaAs layer.

: The tunnel junction is composed of a P-type heavy impurity layer and an N-type heavy impurity layer, where the P-type heavy impurity layer is

P++-GaAs, its impurity concentration ≥ 1E19, N-heavy impurity layer is N++-GaAs, its impurity concentration ≥ 20.

The light-emitting diode chip with electrostatic protection according to claim 8, characterized in that: the thickness of the etching cutoff layer is ≥ 1000 Å.

The light-emitting diode chip with electrostatic protection according to claim 8, characterized in that: an N-type ohmic contact semiconductor layer is further provided between the etching stop layer and the N-type covering layer, which is formed on the N-type covering layer. over the entire surface of the layer.

The light-emitting diode chip with electrostatic protection according to claim 13, characterized in that

: An N-type current transmission layer is also provided between the N-type ohmic contact semiconductor layer and the N-type cladding layer, with an impurity concentration ≥5E17 and a thickness ≥2000nm.

A method for manufacturing a light-emitting diode with electrostatic protection, including the steps:

1) Epitaxial growth: Epitaxial growth is performed on the growth substrate to form an epitaxial wafer, which includes from bottom to top

: Growth substrate, electrostatic protection layer composed of an N-type semiconductor layer and a P-type semiconductor layer

, tunnel junction, etching stop layer, N-type cladding layer, light-emitting layer and P-type cladding layer; 2) Transfer the growth substrate: Provide a conductive substrate, bond it to the P-type covering layer side surface of the epitaxial wafer through a metal bonding layer, remove the growth substrate, and expose the surface of the epitaxial wafer;

3) Make an antistatic protection structure: Define the light extraction area, electrode area and electrostatic protection zone on the surface of the exposed epitaxial wafer, and remove the electrostatic protection layer, tunnel junction and etching cutoff layer in the light extraction area and electrode area;

4) Preparation of electrodes: Make a first N-type ohmic contact electrode in the electrode area on the surface of the epitaxial wafer, make a second N-type ohmic contact electrode on the electrostatic protective layer, and make the etching stop layer, tunnel junction, electrostatic The protective layer and the second N-type ohmic contact electrode form an anti-static protection structure. When the light-emitting diode is subjected to electrostatic reverse bias, the anti-static protection structure works, and the current passes through the first N-type ohmic contact electrode and the electrostatic protection structure to the second The N-type ohmic contact electrode prevents the light-emitting layer from being damaged due to excessive electrostatic reverse bias.