JP2001176823A - Method for manufacturing nitride semiconductor chip - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for obtaining a nitride semiconductor chip with superior light emission performance, without spoiling the crystallinity of a nitride semiconductor and cutting a wafer into a desirable shape to desirable size in good yield, by preventing a cut surface and an interface from cracking or chipping, when a nitride semiconductor wafer which has its substrate made of a nitride semiconductor and includes an active layer emitting light is divided into chips. SOLUTION: This method for obtaining a semiconductor chip from a wafer includes on the nitride semiconductor substrate the nitride semiconductor layer in a multilayered structure with an active layer sandwiched between a p-type layer and an n-type layer through crystal growth. Furthermore, the method has a stage for forming an (A)-th split groove on the crystal growth surface of the wafer, and a stage for forming a split groove narrower than the (A)-th split groove. A semiconductor chip division is carried out by using the different kinds of split grooves. Especially, the nitride semiconductor substrate is doped with chlorine to facilitate chip division.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for dividing a nitride semiconductor chip from a wafer with a high yield.

[0002]

2. Description of the Related Art Conventionally, nitride semiconductors have been used or studied as light emitting devices or high power devices. For example, in the case of a light-emitting element, it can be used as a light-emitting element having a wide range from blue to orange by adjusting the composition of the light-emitting element. In recent years, a blue light emitting diode or a green light emitting diode has been put to practical use utilizing its characteristics, and a blue-violet semiconductor laser has been developed as a nitride semiconductor laser element. Such a nitride semiconductor light emitting device or a nitride semiconductor electronic device device is mainly manufactured on a sapphire substrate. In recent years, there has been a tendency for nitride semiconductor laser devices and the like to be manufactured on a nitride semiconductor substrate from the viewpoint of oscillation life. Also,
When a nitride semiconductor substrate is used, an electrode can be formed on the back surface of the nitride semiconductor substrate, and one chip is occupied by reducing the area of the electrode as compared with the case using an insulating substrate. Since the area can be reduced, the number of chips to be taken from one wafer can be increased.

[0003]

However, a structure for growing a nitride semiconductor light emitting device on a nitride semiconductor substrate has only recently begun, and industrially, how to grow a nitride semiconductor light emitting device on a nitride semiconductor substrate has been improved. The issue was how to divide the semiconductor element into chips. This is because the nitride semiconductor substrate is very hard, so that it is very hard to be broken except in the cleavage direction, and even if it is broken, cracks and chippings are apt to be generated on the cut surface, so that it was not possible to divide the chip neatly.

In Japanese Patent Application Laid-Open No. H11-4048, when a nitride semiconductor layer including an active layer is laminated on a nitride semiconductor substrate, the cleavage planes of the nitride semiconductor layer and the nitride semiconductor substrate can be matched with each other. It introduces that it can be easily cut at the M-plane {11-00}, which is the cleavage plane of the nitride semiconductor substrate. Here, there are three types of M-planes, which are cleavage planes of the nitride semiconductor, with respect to the (0001) substrate, and similarly, the cleavage direction (<
11-20> direction).

However, it is not the cleavage direction <1-10
When the chip is divided along the 0> direction by a normal method, the chip is often broken in a direction shifted by 30 degrees (<11-20> direction) depending on how the scriber or dicer presses the blade. there were.

[0006] In addition, in the usual way, <11
-20> Even if the chip is divided along the direction,
Or, depending on how to apply the contact stress of the blade of the dicer,
Cleavage was sometimes performed in a direction shifted by 60 degrees different from the intended direction.

Although the cleavage in the <11-20> direction is a very effective direction for dividing the chip, there are three types of cleavage in the C plane, and the cleavage direction is 90.
Since they are not perpendicular to each other in degree, the shape of the chip division was influenced by the manner (direction) of applying the contact stress of the blade at the time of chip division. For this reason, the nitride semiconductor element grown on the nitride semiconductor substrate cannot be simply divided into a desired chip shape with a high yield by the ordinary chip dividing method.

[0008]

According to a method of manufacturing a nitride semiconductor chip of the present invention, a p-type layer and an n-type layer are formed on a nitride semiconductor substrate.
In a method of manufacturing a nitride semiconductor chip from a wafer on which a nitride semiconductor layer having a multilayer structure having an active layer sandwiched by mold layers is crystal-grown, an A-th groove is formed on a crystal growth surface of the wafer. And a step of forming a split groove at a position corresponding to the A-th split groove and smaller than the A-th split groove width, and dividing the semiconductor chip along the split groove. It is characterized by.

In the method of manufacturing a nitride semiconductor chip according to the present invention, the step of forming the narrow split groove includes forming a B-th split groove on the substrate surface of the wafer at a position coinciding with the A-th split groove. The process is characterized in that

As a result, since the grown film and the substrate are nitride semiconductors of the same type, they have the same cleavage characteristics,
Also, in order for the cracked line broken by the B-th split groove to break at the shortest cutting distance, the A-th split line must be cut from the bottom of the narrow B-th split groove.
This is because it has no choice but to reach somewhere at the bottom of the split groove, preventing cleavage in an unintended direction and cutting into a desired chip shape. In other words, the reason why the widths of the split grooves are different is that when a cracked line split from the B-th split groove having a small split groove width reaches the A-th split groove having a large split groove width, the split line becomes the B-th split groove. Even if it splits off from just above the groove and splits obliquely, the diagonally split crack line can reach the bottom of the A-th split groove because the A-th split groove width is wide. In this way, the defective rate of the chip shape can be reduced.

The reason why the A-th groove having a large groove width is formed on the side opposite to the nitride semiconductor surface (the crystal growth surface side) is to increase the area of the nitride semiconductor surface. As a result, the area of the n-electrode can be increased, and the light emitted from the light-emitting layer can be reflected by the metal constituting the n-electrode, and the light extraction efficiency from the translucent p-electrode can be increased.
Also, the heat dissipation during mounting is excellent.

In the method of manufacturing a nitride semiconductor chip according to the present invention, the step of forming the narrow split groove may include forming a C-shaped split groove at a position coincident with the A-th split groove in the bottom of the A-th split groove. The process is characterized by forming a groove. As a result, since both the grown film and the substrate are nitride semiconductors of the same type, they have the same cleavage characteristics, and the
Is formed almost along the center line of the bottom of the split groove, the crack line split by the C-th split groove is broken along the portion locally thinned by the A-th split groove. This is because cleavage in the direction can be prevented, and the chip can be cut into a desired chip shape.

The method of manufacturing a nitride semiconductor chip according to the present invention is characterized in that the A-shaped groove is formed deeper than the active layer position from the crystal growth surface side. Thus, even if chipping or cracking occurs during chip division, the light emitting layer is not damaged and the incidence of element failure can be reduced.

In the method for manufacturing a nitride semiconductor chip according to the present invention, a pair of notches are formed at the bottom of the A-th groove or at the edge of the wafer.

In the method for manufacturing a nitride semiconductor chip according to the present invention, the nitride semiconductor substrate contains at least chlorine.

In the method of manufacturing a nitride semiconductor chip according to the present invention, the concentration of the chlorine contained is 1 × 10 ¹⁴ / cm ³ . This allows at least 1 ×
By ping, completely de chlorine - - 10 ¹⁴ / cm ³ or more chlorine concentration de could be compared to the ping and non nitride semiconductor substrate, easily divide the substrate.

Further, when a thick nitride semiconductor film (for example, 300 μm) is formed on a seed substrate (for example, sapphire substrate) by chlorine doping by HVPE,
The amount of warpage caused by the difference in thermal expansion coefficient between the substrate and the thick film was smaller than that of the same thick nitride semiconductor film in which no chlorine was doped on the same seed substrate. Although the reason is not clear, it is considered that the bonding force between the group III atom and the group V atom constituting the nitride semiconductor substrate is weakened by chlorine. Since most of the total film thickness of the element chip is occupied by the substrate, chlorine doping for facilitating element division is very effective.

Since a nitride semiconductor substrate containing chlorine or a nitride semiconductor thick film containing chlorine is easier to divide than a nitride semiconductor substrate or a nitride semiconductor thick film containing no chlorine, The cutting distance can be divided from 200 μm or less.

In the method for manufacturing a nitride semiconductor chip according to the present invention, the direction of the dividing groove may be a nitride semiconductor.
> Direction, <1-100> direction, <0001> direction, <0
−111> direction or a direction of 57.6 ° from the <01-10> direction.

In the method for manufacturing a nitride semiconductor chip according to the present invention, if the shape of the nitride semiconductor chip is a rectangle and the long side of the rectangle is L and the short side is S, L = <11−
20> direction, S = <1-100> direction, L = <0001
> Direction, S = <2-1-10> direction, L = <01-10>
> Direction, S = <2-1-10> direction, L = <0001>
The direction is one of S = <01-10> directions. By providing the above combination, it is possible to form a large number of grooves with the direction in which chip division is easy as the long side, and conversely, it is possible to form the grooves with the direction in which chip division is difficult as the short side. As a result, it is possible to suppress shape defects caused by chip division.

According to the method of manufacturing a nitride semiconductor chip of the present invention, the ratio (L /
S) is 1.01 or more and 4 or less. This makes it possible to efficiently apply a force to the split groove based on the principle of leverage, thereby facilitating chip division. In particular, by combining with the technique of selecting the direction of the short side and the long side, it is possible to efficiently apply the force to the split groove by the leverage principle on the short side where the chip division is difficult, thereby facilitating the chip division. can do.

In the method for manufacturing a nitride semiconductor chip according to the present invention, the nitride semiconductor substrate is a GaN substrate.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Generally, as a method for growing a nitride semiconductor crystal, a metal organic chemical vapor deposition (hereinafter referred to as MO) method is used.
VCD method), molecular beam epitaxy method (hereinafter, MBE method),
Usually, it is performed by a hydride vapor phase epitaxy method (hereinafter, HVPE method), and any crystal growth method may be used. In the following, a GaN substrate is used as a substrate and MO is used as a growth method.
Examples of a nitride semiconductor light emitting diode and a nitride semiconductor laser diode manufactured by using the CVD method will be described.

[0024] The substrate may be a substrate which is composed of a nitride _{semiconductor, Al x Ga y In z N} (x + y +
z = 1) It may be a substrate. Moreover, Al _x Ga _y In _z
About 10% of nitrogen element of N (x + y + z = 1) substrate
Less than or equal to (but hexagonal)
It may be replaced with another element of s and Sb. In particular, in the case of a nitride semiconductor laser, a layer having a lower refractive index than the cladding layer needs to be in contact with the outside of the cladding layer in order to make the vertical and horizontal modes have a single peak. It is best used.

In the following embodiments, a C-plane substrate of a nitride semiconductor is described, but an A-plane substrate, an R-plane substrate, and an M-plane substrate may be used. However, the effect of the chip division according to the present invention was most observed on the C-plane substrate. Further, even if the substrate is not a perfect C-plane substrate, the same effect can be obtained if the substrate has an off angle of 2 degrees or less from the C-plane. The off angle was the same for the A-plane substrate, the R-plane substrate, and the M-plane substrate.

(Embodiment 1) In Embodiment 1, a method of manufacturing a nitride semiconductor light emitting diode element and chip division will be described.

FIG. 1 shows a C-plane (0001) n-type GaN substrate 100, an n-type GaN buffer layer 101, and an n-type Al _x1 Ga
_1-x1 N cladding layer 102, active layer 103, p-type Al _x2
It comprises a Ga _{1 -x2} N cladding layer 104, a p-type GaN contact layer 105, an n-type electrode 106, a p-type electrode 107, an A-th split groove 108, and a B-th split groove 109.

The nitride semiconductor light emitting diode shown in FIG.
A method of manufacturing the device will be described. First, the HVPE method
Thick GaN layered on a plate (eg, sapphire substrate)
Then, the sapphire substrate is peeled off by polishing, and the thickness is 4
C-plane (0001) n-type G of 00 μm and size of 2 inch φ
An aN substrate 100 was manufactured. N-type pole of the n-type GaN substrate
Is obtained by doping Si, and the S
The concentration of i is 2 × 10 ¹⁸/ Cm^ThreeMet. Furthermore, before
About 2 × 10 in the n-type GaN substrate¹⁷/ Cm^ThreeOf chlorine
-Pinging.

Next, the above-mentioned n-type GaN
The substrate 100 is set, and n-type G is grown at a growth temperature of 1050 ° C.
The aN buffer layer 101 was formed to 1 μm. This n-type Ga
The N-buffer layer is a layer provided for the purpose of alleviating the surface distortion of the n-type GaN substrate, and improving the surface morphology and the surface unevenness (flattening) generated when the n-type GaN substrate is peeled from the seed substrate. , It doesn't matter. However, GaN
When chlorine is doped on the substrate, the surface morphology tends to deteriorate. Therefore, it is preferable to provide a GaN buffer layer as in this embodiment. After forming the n-type GaN buffer layer 101, the n-type Al _x1
A Ga _1-x1 N layer 102 was formed. In the present embodiment, X
It was prepared with 1 = 0.

Next, the temperature of the substrate is lowered to about 700 ° C. to 800 ° C., and 3 cycles of 4 nm thick In _0.35 Ga _0.65 N
An active layer (multiple quantum well layer) 103 composed of a well layer and a 6 nm thick In _0.02 Ga _0.98 N barrier layer is grown.
At that time, SiH ₄ may or may not be supplied. Further, the barrier layer may be composed of GaN.
Next, the substrate temperature was raised again to 1050 ° C.
A 0 nm p-type Al _x2 Ga _1-x2 N layer 104 is grown. In the present embodiment, X2 = 0.2. afterwards,
A 0.3 μm-thick p-type GaN contact layer 105 was grown.

Although the active layer 103 of this embodiment has a multi-quantum well structure having three periods, it may have another periodic structure or a single quantum well structure having only a well layer.
The active layer may be composed of In _y Ga _1-y N, may be changed the In composition in accordance with a desired emission wavelength.

The active layer is a single quantum well and the emission wavelength is 37
When the thickness is less than 0 nm, the well layer is preferably made of GaN, and at least an impurity having a polarity must be doped. The n-type cladding layer 10
2 and the p-type cladding layer 104 must be made of a nitride semiconductor containing at least Al.

When the active layer is composed of multiple quantum wells and the emission wavelength is 370 nm or less, the well layer is Ga
The barrier layer must be made of N, and the barrier layer must be a nitride semiconductor containing at least Al, and at least either the well layer or the barrier layer must be doped with a polar impurity. Further, the n-type cladding layer 102 and the p-type cladding layer 104 may or may not be made of a nitride semiconductor containing Al.
This is because carriers are sufficiently confined by the nitride semiconductor barrier layer containing Al having a multiple quantum well structure.

The polar impurities in the well layer or the barrier layer in the active layer are Si, Ge, O, C, Zn, B
E or Mg is preferred. It is preferable that the p-type impurity concentration of the p-type GaN contact layer 105 be increased toward the position where the p-type electrode 107 is formed.
This reduces the contact resistance due to the formation of the p-type electrode. Further, in order to remove residual hydrogen in the p-layer which prevents activation of Mg which is a p-type impurity, a trace amount of oxygen may be mixed during growth of the p-type layer.

As described above, the p-type GaN contact layer 1
After growing 05, the inside of the reactor of the MOCVD apparatus was changed to total nitrogen carrier gas and NH ₃ , and the temperature was lowered at 60 ° C./min. When the substrate temperature reaches 850 ° C., NH ₃
Was stopped at the substrate temperature for 5 minutes and then lowered to room temperature. The holding temperature of the substrate is 65
The temperature was preferably between 0 ° C. and 900 ° C., and the waiting time was preferably 3 minutes or more and 15 minutes or less. Further, the reaching speed of the temperature drop is preferably 30 ° C./min or more.

As a result of evaluating the grown film thus manufactured by Raman measurement, it was found that the p-type characteristics were already obtained after the growth by the above-mentioned method without using the conventionally used p-type annealing. Was showing. Further, the contact resistance due to the formation of the p-type electrode was also reduced.

SIMS (secondary ion mass spectrosc)
opy) As a result, the residual hydrogen concentration was 3 × 10 ¹⁸ / cm ³ or less near the outermost surface of the p-type GaN contact layer 105. According to an experiment by the inventors, when the substrate temperature was lowered to room temperature in an NH ₃ atmosphere after forming the grown film, the residual hydrogen concentration was high near the outermost surface of the grown film, so that It is considered that the residual hydrogen concentration is caused by the NH ₃ atmosphere after the growth is completed. It is known that this residual hydrogen prevents activation of Mg which is a p-type impurity. The residual hydrogen concentration is 5 × 10 ¹⁹ / cm ³
The following is preferred.

After the growth of the p-type GaN contact layer 105, the carrier gas is replaced with N ₂ , the supply of NH ₃ is stopped, and the growth temperature is maintained for a predetermined time to promote the p-type GaN contact layer 105. As a result, the residual hydrogen concentration near the outermost surface of the grown film was reduced, and the contact resistance was reduced. As a method of further reducing the contact resistance due to the formation of the p-type electrode,
Preferably, the vicinity of the outermost surface of the growth film (the outermost surface of the p-type layer) is removed by etching, and a p-type electrode is formed on the removed surface. The layer thickness for removing the outermost surface of the grown film (the outermost surface of the p-type layer) is 10
nm or more, and there is no particular upper limit, but it is preferable that the residual hydrogen concentration in the vicinity of the removed surface be 5 × 10 ¹⁹ / cm ³ or less.

Next, chip division of a wafer on which the above-described nitride semiconductor light emitting diode device is formed will be described.
The first embodiment is chip division in the case where the A-th split groove depth is formed deeper than the position of the nitride semiconductor light emitting layer. Here, the crystal growth side refers to the side opposite to the substrate side.

First, the GaN substrate side of the above wafer is polished by a polishing machine to make the thickness of the chlorinated GaN substrate 100 μm and mirror-finished. Next, the wafer is etched with a mixed solution of sulfuric acid containing hydrofluoric acid or hot phosphoric acid. This etching process
Removal of surface distortion and oxide film caused by polishing, p
This is performed to reduce the contact resistance of the mold and n-type electrodes and to prevent electrode peeling.

Next, the surface on the crystal growth side of the wafer is subjected to mask processing by lithography, and the wafer is set in a reactive ion etching apparatus. By dry etching, a depth of 0.1 mm was formed on the growth surface along the <1-100> direction.
5 μm, line width 10 μm, pitch 350 μm, <11−
20> direction, depth 0.5 μm, line width 10 μm,
The A-th split groove 108 having a pitch of 250 μm was formed.
Then, the mask is removed and the p-type GaN contact layer 1 is removed.
05, in the order of Pd (14 nm) / Au (2 nm)
A translucent p-type electrode 107 and an Au pad electrode are formed. At this time, a p-electrode portion was formed in a pattern by using a lithography technique. Next, the wafer on which the p-electrode was formed was annealed at 550 ° C. in a N ₂ atmosphere while introducing a small amount of oxygen. As a result, the contact resistance was reduced by forming the p-type electrode.

Next, GaN is placed on the scriber table.
It is attached with the substrate side up and fixed with a vacuum chuck.
After fixing, a scriber is used to form a pitch of 350 μm, a depth of 5 μm, a line width of 5 μm, and a pitch of 25 μm on the GaN substrate side surface.
B-th split groove 10 having a thickness of 0 μm, a depth of 5 μm, and a line width of 5 μm
9 were formed in the <1-100> and <11-20> directions, respectively. In this way, scribe lines are formed so as to form chips of 350 μm × 250 μm square, and the B-th groove 109 is formed. However, the B-th groove 109
Is formed such that the B-th split groove 109 coincides substantially with the line width of the A-th split groove 108.

After scribing, the vacuum chuck is released, the wafer is removed from the table, and an n-type electrode 106 of W (15 nm) / Al (150 nm) is formed on the entire surface of the wafer on the GaN substrate side. Then, an adhesive sheet is attached to the surface on the crystal growth side (the surface on which the p-type electrode is formed), and is pressed lightly from the GaN substrate side with a roller to form a 2 inch φ.
A large number of chips of 350 μm × 250 μm square were obtained from the wafer. Cracks, chipping, etc., did not occur on the cut surface of the chip, and when a product having no external defect was taken out, the yield was 97% or more.

In the present embodiment, the reason why the chip can be divided into a desired shape with a high yield is that a nitride semiconductor film including a light emitting layer is formed on a similar nitride semiconductor substrate doped with chlorine, and Without cutting all at once, forming the bottom of the A-th split groove deeper than the position of the nitride semiconductor light emitting layer;
Is made narrower than the A-th groove width. That is, since both the grown film and the substrate are nitride semiconductors of the same system, they have the same cleavage characteristics, and the chlorine is doped in the substrate, so that the division is facilitated. The groove bottom is deeper than the nitride semiconductor light emitting layer position,
Since the A-th split groove has a wider groove width than the B-th split groove, in order for the split line split by the B-th split groove to be broken at the shortest cutting distance, the A-th split groove must be cut from the bottom of the B-th split groove. This is because it has no choice but to reach somewhere at the bottom of the split groove, preventing cleavage in an unintended direction and cutting into a desired chip shape. Further, since the bottom of the A-th groove is deeper than the position of the nitride semiconductor light emitting layer, even if chipping or cracking occurs at the time of chip division, the light emitting layer is not damaged and element failure occurs. Rate can be reduced.

The reason why the width of the A-th split groove is different from the width of the B-th split groove is that, as described above, the cracked line split from the B-th split groove having a small split groove width is different from the A-th split groove having a wide split groove width. When reaching the split groove, even if the split line is displaced from immediately above the B-th split groove and splits in an oblique direction, since the A-th split groove width is large, the diagonally split split line becomes the A-th split groove. Of the groove can be reached. In this way, the defective rate of the chip shape can be reduced.

The reason why the A-th split groove having a large groove width is formed on the side opposite to the nitride semiconductor surface (the crystal growth surface side) is to increase the area of the nitride semiconductor surface. As a result, the area of the n-electrode can be increased, and the light emitted from the light-emitting layer can be reflected by the metal constituting the n-electrode, and the light extraction efficiency from the translucent p-electrode can be increased.
Also, the heat dissipation during mounting is excellent.

When the effect of chlorine doping in the nitride semiconductor substrate was examined, at least 1 × 10 ¹⁴ / c
By doping a chlorine concentration of m ³ or more, the substrate could be divided more easily than a nitride semiconductor substrate having no chlorine doped. Also, HVP
A thick nitride semiconductor film (for example, 30 nm) obtained by performing chlorine doping on a seed substrate (for example, a sapphire substrate) by the E method.
0 μm), the amount of warpage caused by the difference in thermal expansion coefficient between the substrate and the thick film is smaller than that of the same thick nitride semiconductor film in which no chlorine is doped on the same seed substrate. Was. Although the reason is not clear, it is considered that the bonding force between the group III atom and the group V atom constituting the nitride semiconductor substrate is weakened by chlorine. Since most of the total thickness of the element chip is occupied by the substrate, chlorine film which facilitates element division is used.
Ping is very effective.

In the present embodiment, reactive ion etching is used to form the A-th groove, but the groove may be formed by a physical method such as half cutting by dicing, scriber, or the like. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in the present embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the side surface of the groove due to the formation of the groove can be suppressed. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scribe is used to form the B-th groove width. However, an etching method, dicing, or the like may be used. However, scribe is most preferable for the B-th groove in the present embodiment.
This is because a groove can be formed quickly with a narrow groove width.

In the present embodiment, the GaN substrate is polished to a thickness of about 100 μm. However, according to experiments performed by the present inventors, the thickness of the chlorine-doped GaN substrate is preferably 200 μm or less. More preferably 150
μm or less was preferred. Doping chlorine in nitride semiconductor
Although the pinging facilitates the division, it is preferable to reduce the thickness of the substrate in order to cleave in a desired direction with a good yield. This is because the thickness of the GaN substrate is usually 300 μm to 600 μm, whereas the thickness of the nitride semiconductor film including the light emitting layer laminated on the GaN substrate is about several μm. Because it is occupied by.

As in the present embodiment, it is most preferable to divide the wafer into chips at the position where the center position of the groove width of the A-th split groove coincides with the center position of the groove width of the B-th split groove. However, if the thickness of the wafer (the thickness of the GaN substrate) is too large, the wafer tends to be deviated from the above position and crack.
Further, at a position where the A-th groove and the B-th groove do not coincide with each other, the wafer (substrate) needs to be polished and thinned because it tends to be hardly broken. The lower limit of the thickness of the GaN substrate is not particularly limited, but if it is too thin, the wafer will be broken during the process for device fabrication, so the lower limit of the thickness of the GaN substrate is desirably 50 μm or more. In addition to polishing the entire chlorine-doped GaN substrate to make it thinner, a method of partially thinning the chlorin-doped GaN substrate may be performed by using a bottom portion of an A-th split groove and a B-th split groove. May be reduced in the cutting distance with the bottom. At this time, the cutting distance was GaN doped with chlorine.
Like the thickness of the substrate, the thickness is preferably 200 μm or less, more preferably 150 μm or less, and 50 μm or more.

Further, the GaN substrate doped with chlorine is polished to a thickness larger than 200 μm, which is easy to cut, and the cutting distance between the A-th and B-th split grooves is set to 20 mm.
It may be 0 μm or less. As a result, it is difficult to cut the portion other than the split groove portion, and it is possible to prevent cracking and chipping from occurring at the time of chip division.

In addition to the dividing groove of the present embodiment, a scribe line may be formed in the A-th dividing groove as the C-th dividing groove to divide the chip. Further, as shown in FIG. 3, a pair of notched grooves may be formed at the edge of the A-th groove to divide the element. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided in the bottom of the A-th split groove. In this case, the total thickness of the wafer is preferably 150 μm or less, or the cutting distance from the bottom of the A-th split groove to the bottom of the B-th split groove is preferably 150 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is performed in the substrate.

(Embodiment 2) Embodiment 2 is directed to a case where the depth of the A-th dividing groove of Embodiment 1 is larger than the interface position between the nitride semiconductor film and the nitride semiconductor substrate. The chip division will be described. Here, the crystal growth side is
It refers to the opposite side to the substrate side.

FIG. 4 shows a C-plane (0001) n-type GaN substrate 200, an n-type GaN buffer layer 201, and an n-type Al _x1 Ga
_1-x1 N cladding layer 202, active layer 203, p-type Al _x2
It comprises a Ga _{1 -x2} N cladding layer 204, a p-type GaN contact layer 205, an n-type electrode 206, a p-type electrode 207, an A-th groove 208, and a B-th groove 209. The GaN substrate 200 is doped with a chlorine concentration of 1 × 10 ¹⁸ / cm ³ .

The method of manufacturing the nitride semiconductor light emitting diode of FIG. 4 is the same as that of the first embodiment. Hereinafter, chip division of a wafer on which the nitride semiconductor light emitting diode device is formed will be described.

First, the GaN substrate side of the above-mentioned wafer is polished by a polishing machine to make the thickness of the GaN substrate doped with chlorine 200 μm and mirror-finished. The reason why the GaN substrate surface is mirror-finished (made transparent) is that the formation positions of the split grooves described below can be easily confirmed from the back surface side, and the adjustment of the formation positions of the p-electrode and the n-electrode can be easily performed. To do that. Next, the wafer is etched with a mixed solution of sulfuric acid containing hydrofluoric acid or hot phosphoric acid. This etching treatment is performed to remove surface distortion and oxide film caused by polishing, to reduce the contact resistance of the p-type and n-type electrodes, and to prevent electrode peeling.

Next, the surface on the crystal growth side of the wafer is masked by lithography and set in a reactive ion etching apparatus. By dry etching, a depth of 4 μm, a line width of 20 μm, and a pitch of 350 μm, a depth of 4 μm, a line width of 20 μm, and a pitch of 15 μm were formed on the crystal growth surface.
0 μm, the A-th split grooves 208 are respectively <1-10
0> direction and <11-20> direction. Thereafter, the mask is removed and the p-type GaN contact layer 205 is removed.
A translucent p-type electrode 207 and an Au pad electrode are patterned in the order of Pd (7 nm) / Ni (7 nm) using lithography technology.

Next, while introducing a small amount of oxygen, 600
Annealed at a N ₂ atmosphere at ° C. - was le. As a result, the contact resistance was reduced by forming the p-type electrode. Subsequently, the wafer is turned over, and an n-type electrode 206 of Ti (15 nm) / Mo (150 nm) is formed on the GaN substrate side by lithography.

At this time, an n-type electrode pattern is formed directly opposite to the formation position of the p-type electrode pattern on the crystal growth side, and the electrodes are covered with each other to form a split groove. Match no areas. Subsequently, the GaN substrate is stuck on the table of the scriber with the GaN substrate side facing up and fixed with a vacuum chuck. After fixing, G
On a surface on the aN substrate side (n-type GaN substrate 200), a pitch of 350 μm, a depth of 5 μm, a line width of 5 μm, and a pitch of 150 μm.
B-th groove 209 having a thickness of 5 μm, a depth of 5 μm, and a line width of 5 μm
Were formed along the <1-100> and <11-20> directions, respectively. 350μm × 150μ
A scribe line is formed so as to form an m-shaped chip, and a B-th split groove 209 is formed.

After scribing, the vacuum chuck was released, the wafer was removed from the table, and the wafer was lightly pressed from the GaN substrate side with a roller to obtain a large number of chips of 350 μm square from the wafer of 2 inch φ. Cracks, chipping, etc., did not occur on the cut surface of the chip, and a product having no external defect was taken out. The yield was 98% or more.

In the present embodiment, the reason why the chip can be divided into a desired shape with a high yield is that a nitride semiconductor film including a light emitting layer is formed on a similar nitride semiconductor substrate doped with chlorine, and Forming the A and B split grooves without cutting at a time, forming the bottom of the A split groove deeper than the interface between the nitride semiconductor film and the substrate, This is because the width is smaller than the width of the A-th dividing groove. That is, since both the grown film and the substrate are nitride semiconductors of the same system, they have the same cleavage characteristics, and the chlorine is doped in the substrate, so that the division is facilitated. The groove bottom is deeper than the interface between the nitride semiconductor film and the substrate,
Since the A-th split groove has a wider groove width than the B-th split groove, in order for the split line split by the B-th split groove to be broken at the shortest cutting distance, the A-th split groove must be cut from the bottom of the B-th split groove. This is because it has no choice but to reach somewhere at the bottom of the split groove, preventing cleavage in an unintended direction and cutting into a desired chip shape. In addition, since the bottom of the A-th groove is deeper than the interface between the nitride semiconductor film and the substrate, even if chipping or cracking occurs during chip division, the light emitting layer is not damaged, and the device is not damaged. The occurrence rate of defects can be reduced.

Further, since the bottom of the A-th groove reaches the nitride semiconductor substrate doped with chlorine,
The chip division is a division of the nitride semiconductor substrate itself in which chlorine is doped, and can be divided more easily than a nitride semiconductor substrate in which chlorine is not doped at all. The effect of chlorine doping in the nitride semiconductor substrate is the same as in the first embodiment.

The reason why the width of the A-th groove is different from the width of the B-th groove is as described above. When reaching the split groove, even if the split line is displaced from immediately above the B-th split groove and splits in an oblique direction, since the A-th split groove width is large, the diagonally split split line becomes the A-th split groove. Of the groove can be reached. In this way, the defective rate of the chip shape can be reduced.

The reason why the A-th split groove having a large groove width is formed on the side opposite to the nitride semiconductor surface (the crystal growth surface side) is to increase the area of the nitride semiconductor surface. As a result, the area of the n-electrode can be increased, and the light emitted from the light-emitting layer can be reflected by the metal constituting the n-electrode, and the light extraction efficiency from the translucent p-electrode can be increased.
Also, the heat dissipation during mounting is excellent.

In the present embodiment, reactive ion etching is used for forming the A-th groove, but the groove may be formed by a physical method such as half cutting by dicing, scriber or the like. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in the present embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scribe is used to form the B-th split groove width.
Dicing or the like may be used. However, scribing is most preferable in forming the B-th groove. This is because a groove can be formed quickly with a narrow groove width.

Further, in this embodiment, the scribe lines are formed in a lattice shape. However, as shown in FIG. 3, a pair of notched grooves may be formed only at the edge portion of the wafer to divide the elements. In this case, the total thickness of the wafer is 150 μm.
It is preferable that the cutting distance from the bottom of the A-th split groove to the bottom of the B-th split groove is 150 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is performed in the substrate.

In the present embodiment, since the wafer is divided into chips at the locally thinned groove portions by forming the A-th and B-th split grooves, the B-th and the B-th split grooves are separated from the bottom of the A-th split groove. It is preferable that the cutting distance to the bottom of the split groove is short. The cutting distance is preferably 200 μm or less, more preferably 150 μm or less, like the thickness of the GaN substrate subjected to chlorine doping. The lower limit of the thickness of the cutting distance is not particularly limited. However, if the thickness is too small, the wafer will be broken during the process for device formation. Therefore, the lower limit of the cutting distance is desirably 50 μm or more.

Further, the GaN substrate doped with chlorine is polished to a thickness greater than 200 μm, which is easy to cut, and the cutting distance between the A-th and B-th split grooves is set at 2 mm.
It may be 00 μm or less. As a result, it is difficult to cut the portion other than the split groove portion, and it is possible to prevent cracking and chipping from occurring at the time of chip division.

In addition to the dividing groove of the present embodiment, a scribe line may be formed as a C-th dividing groove in the A-th dividing groove to divide the chip. Further, as shown in FIG. 3, a pair of notched grooves may be formed at the edge of the A-th groove to divide the element. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided in the bottom of the A-th split groove. In this case, the total thickness of the wafer is preferably 150 μm or less, or the cutting distance from the bottom of the A-th split groove to the bottom of the B-th split groove is preferably 150 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is performed in the substrate.

(Embodiment 3) In Embodiment 3, a description will be given of chip division in the case where the depth of the A-th dividing groove in Embodiment 1 is smaller than the position of the nitride semiconductor light emitting layer. . Here, the crystal growth side refers to the side opposite to the substrate side.

FIG. 5 shows a C-plane (0001) n-type GaN substrate 300, an n-type GaN buffer layer 301, and an n-type Al _x1 Ga
_1-x1 N clad layer 302, active layer 303, p-type Al _x2
It comprises a Ga _{1 -x2} N cladding layer 304, a p-type GaN contact layer 305, an n-type electrode 306, a p-type electrode 307, an A-th split groove 308, and a B-th split groove 309. The GaN substrate 300 is doped with a chlorine concentration of 1 × 10 ¹⁴ / cm ³ .

The method of manufacturing the nitride semiconductor light emitting diode of FIG. 5 is the same as that of the first embodiment. First, the GaN substrate side of the above-mentioned wafer is polished by a polishing machine to make the thickness of the chlorine-doped GaN substrate 150 μm and mirror-finished. The reason why the GaN substrate surface is mirror-finished (made transparent) is that the formation positions of the split grooves described below can be easily confirmed from the back surface side, and the p-electrode and the n-type
This is for facilitating the adjustment of the electrode formation position. next,
A mixed solution consisting of sulfuric acid containing hydrofluoric acid or hot phosphoric acid,
Etching the wafer. This etching treatment is performed to remove surface distortion and oxide film caused by polishing, to reduce the contact resistance of the p-type and n-type electrodes, and to prevent electrode peeling.

Next, the wafer is subjected to a mask process by a lithography method, and is set in a reactive ion etching apparatus with the crystal growth side (p-type GaN contact layer) facing upward. By dry etching, a depth of 0.2 μm, a line width of 20 μm, and a pitch of 35 μm were formed on the crystal growth side of the wafer.
The 0-μm A-th groove 308 was formed in the <1-100> direction and the <11-20> direction in the lattice shape shown in FIG. After that, the mask is removed, and the translucent p-type electrode 307 and the Au pad electrode are patterned on the p-type GaN contact layer 305 in the order of Pd (4 nm) / Mo (3 nm) by lithography technology. After the formation, while introducing a small amount of oxygen, annealed at 500 ° C. in N ₂ atmosphere.
Done. As a result, the contact resistance was reduced by forming the p-type electrode. Next, the wafer was turned over, and Ti (15 nm) / Al
A (150 nm) n-type electrode 306 is patterned by lithography. At this time, the n-type electrode pattern is located on the side opposite to the position where the p-type electrode pattern is formed on the crystal growth side.
Are formed, and the regions where the electrodes are not covered with each other are matched to form a split groove.

Next, an adhesive sheet is attached to the crystal growth side of the wafer, attached to the scriber table with the GaN substrate side up, and fixed with a vacuum chuck. After fixing,
Using a diamond needle of a scriber, scribe is performed once on the GaN substrate side surface (n-type GaN substrate 300) at a pitch of 350 μm, a depth of 5 μm, and a line width of 5 μm. Next, scribing is performed in a direction perpendicular to the previous scribing direction. In this way, scribe lines are formed so as to form chips of 350 μm square, and the B-th groove 309 is formed.
To form However, the formation position of the B-th split groove 309 is set to a position substantially coincident with the center line of the line width of the A-th split groove 308, and the forming direction of the A-th split groove and the B-th split groove is <11-20> or <
1-100> direction. It is also preferable that the B-th split groove 309 is formed at a position where the electrode is not covered, similarly to the A-th split groove 308.

After scribing, the vacuum chuck was released, the wafer was detached from the table, and lightly pressed from the GaN substrate side with a roller to obtain a large number of chips of 350 μm square from the wafer of 2 inch φ. . Cracks, chipping, etc., did not occur on the cut surface of the chip, and a product having no external defect was taken out. The yield was 93% or more.

In the present embodiment, the chip can be divided into a desired shape with a good yield because a nitride semiconductor film including a light emitting layer is formed on a similar nitride semiconductor substrate doped with chlorine, and This is because the A-th split groove and the B-th split groove are formed without cutting at once, and the B-th split groove is configured to be narrower than the A-th split groove width. That is, since both the grown film and the substrate are nitride semiconductors of the same system, they have the same cleavage characteristics, and the chlorine is doped in the substrate, so that the division is facilitated. This is because the groove has a wider groove width than the B-th split groove, and is cut into the A-th split groove and the B-th split groove. Further, in order for the cracked line broken by the B-th split groove to be broken at the shortest cutting distance, the crack line is required from the bottom of the B-th split groove to somewhere on the bottom of the A-th split groove above the bottom of the B-th split groove. This is because it can only be reached and is prevented from being cleaved in an unintended direction, and can be cut into a desired chip shape.

The reason why the width of the A-th groove is different from the width of the B-th groove is that, as described above, the cracked line split from the B-th groove having a small width is the A-th groove having a wide width. When reaching the split groove, even if the split line is displaced from immediately above the B-th split groove and splits in an oblique direction, since the A-th split groove width is large, the diagonally split split line becomes the A-th split groove. Of the groove can be reached. In this way, the defective rate of the chip shape can be reduced.

The reason why the A-th groove having a large groove width is formed on the side opposite to the nitride semiconductor surface (the crystal growth surface side) is to increase the area of the nitride semiconductor surface. As a result, the area of the n-electrode can be increased, and the light emitted from the light-emitting layer can be reflected by the metal constituting the n-electrode, and the light extraction efficiency from the translucent p-electrode can be increased.
Also, the heat dissipation during mounting is excellent.

The effect of chlorine doping in the nitride semiconductor substrate is the same as in the first embodiment. In the present embodiment, since the A-th dividing groove does not reach the active layer, the light emitting area can be larger than in the first and second embodiments. In particular, it is effective to cover the bottom portion 308 of the A-th groove 308 with the p-electrode 307.

In this embodiment, reactive ion etching is used to form the A-th groove. However, the groove may be formed by a physical method such as half cutting by dicing, scriber, or the like. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in the present embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scribe is used for forming the B-th groove width.
Dicing or the like may be used. However, scribing is most preferable in forming the B-th groove. This is because a groove can be formed quickly with a narrow groove width.

In this embodiment, the scribe lines are formed in a grid pattern. However, as shown in FIG. 3, a pair of notches may be formed only at the edge of the wafer to divide the elements. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided in the bottom of the A-th split groove. In this case, the total thickness of the wafer is preferably 150 μm or less, or the cutting distance from the bottom of the A-th split groove to the bottom of the B-th split groove is preferably 150 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is performed in the substrate.

In this embodiment, the GaN substrate doped with chlorine is polished to a thickness of about 150 μm. However, as described in the first embodiment, in order to facilitate chip division, Is preferably 200 μm or less, more preferably 150 μm or less, and more preferably 50 μm or more. GaN doped with chlorine
As a method of partially thinning the GaN substrate in addition to polishing the entire substrate to reduce the thickness, the cutting distance between the bottom of the A-th split groove and the bottom of the B-th split groove may be shortened. At this time, the cutting distance is preferably 200 μm or less, more preferably 150 μm or less and 50 μm or more, similarly to the thickness of the GaN substrate on which chlorine doping is performed (Embodiment 4). Then, during the A-th slot, C-th
A method of forming the split groove and dividing the chip will be described.

FIG. 6 shows a C-plane (0001) n-type GaN substrate 400, an n-type GaN buffer layer 401, and an n-type Al _x1 Ga
_1-x1 N cladding layer 402, active layer 403, p-type _Alx2G
a _{1 -x2} N cladding layer 404, p-type GaN contact layer 4
05, an n-type electrode 406, a p-type electrode 407, an A-th split groove 408, and a C-th split groove 409. Ga
The N substrate 400 has a chlorine concentration of 5 × 10 ¹⁵ / cm ³ .

The method of manufacturing the nitride semiconductor light emitting diode of FIG. 6 is the same as that of the first embodiment. The chip division of the wafer on which the nitride semiconductor light emitting diode device is formed will be described. Here, the crystal growth side refers to the side opposite to the substrate side.

First, the GaN substrate side of the above-mentioned wafer is polished by a polishing machine so that the thickness of the chlorin-doped GaN substrate is 130 μm. At this time, the polished surface may or may not be a mirror surface. This is because there is no need to check the split grooves from both sides. Next, the wafer is etched with a mixed solution of sulfuric acid containing hydrofluoric acid or hot phosphoric acid. This etching treatment removes surface distortion and oxide film caused by polishing, and removes p-type,
This is performed to reduce the contact resistance of the n-type electrode and prevent the electrode from peeling.

Subsequently, a translucent p-type electrode 407 is formed on the p-type GaN contact layer 405 in the order of Pd (7 nm) / Au (80 nm) over the entire surface of the wafer, and an Au pad electrode is formed. 450 ° C while introducing oxygen
Was performed in an N ₂ atmosphere. This allows
The reduction of the contact resistance by the formation of the p-type electrode was obtained. Next, turn the wafer upside down, and on the GaN substrate side,
An n-type electrode 406 of Ti (15 nm) / Al (150 nm) is formed on the entire surface of the wafer.

The surface on the crystal growth side of the wafer is subjected to a mask process by lithography technology, and is set in a reactive ion etching apparatus. By dry etching, a depth of 0.2 μm, a line width of 30 μm, and a pitch of 350 μm were formed on the growth surface along the <1-100> direction of the GaN substrate.
And the A-th split groove 408 having a depth of 0.2 μm, a line width of 30 μm, and a pitch of 300 μm along the <11-20> direction (perpendicular to the <1-100> direction), and the p-type electrode 4.
07. The A-th split groove is preferably formed in a portion where the p-type electrode 407 is not covered in consideration of electrode peeling, but in the present embodiment, the A-th split groove and the C-th split groove are formed. Are formed on the same surface, there is no need to provide an electrode uncovered portion for groove alignment. Therefore, in order to simplify the device process, increase the number of chips from a single wafer, and increase the light emitting area, n
Both the electrode and the p-electrode are formed on the entire surface of the wafer without providing an electrode non-covering portion for the dividing groove.

Next, an adhesive sheet is adhered to the surface of the wafer on the GaN substrate side (n-type electrode 406), adhered on the scriber table with the crystal growth side up, and fixed with a vacuum chuck. . After the fixation, the diamond needle of the scriber is used to make a pitch 3 along the center line of the bottom of the A-th groove.
50 μm, 0.1 μm depth, 5 μm line width <1-100
Scribe once in the direction. Next, in the direction perpendicular to the scribe direction (<11-20> direction), once along the substantially central line at the bottom of the A-th groove at a pitch of 300 μm, a depth of 0.1 μm, and a line width of 5 μm. Scribe. In this manner, a scribe line is formed so as to form a chip of 350 μm × 300 μm square, and a C-th split groove 409 is formed.

After scribing, release the vacuum chuck, remove the wafer from the table, and lightly press the wafer from the crystal growth side with a roller to obtain a large number of 350 μm × 300 μm square chips from a 2-inch φ wafer. Obtained. No cracks, chippings, etc. occurred on the cut surface of the chip, and a product with no external defect was taken out.
% Or more.

In the present embodiment, the reason why the chip can be divided into a desired shape with good yield is that a nitride semiconductor film including a light emitting layer is formed on a similar nitride semiconductor substrate doped with chlorine, and This is because the A-th split groove and the C-th split groove are formed without cutting at one time, and the C-th split groove is formed in the A-th split groove. That is, since both the grown film and the substrate are nitride semiconductors of the same type, they have the same cleavage characteristics, and the chlorine is doped in the substrate to facilitate division, and By forming the groove substantially along the center line of the bottom of the A-th split groove, a crack line split by the C-th split groove is broken along a portion locally thinned by the A-th split groove. This is because cleavage in an unintended direction can be prevented, and the chip can be cut into a desired chip shape.

The reason why the A-th split groove having a large groove width is formed on the side opposite to the nitride semiconductor surface (the crystal growth surface side) is to increase the area of the nitride semiconductor surface. This allows n
The electrode area can be increased, and light emitted from the light-emitting layer can be reflected by the metal constituting the n-electrode, so that light extraction efficiency from the translucent p-electrode can be increased. Also,
Excellent heat dissipation during mounting.

The effect of chlorine doping in the nitride semiconductor substrate is the same as in the first embodiment. In the present embodiment, since the C-th dividing groove does not reach the active layer, the light emitting area can be larger than in the first and second embodiments. In particular, it is effective to cover the bottom portion 408 of the A-th groove and the bottom portion 409 of the C-th groove with the p-electrode 407.

In the present embodiment, reactive ion etching is used to form the A-th groove, but the groove may be formed by a physical method such as half cutting by dicing, scriber, or the like. However, the A-th groove is
Since the width of the groove C must be wider than the width of the groove C, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in this embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scribe is used to form the C-th groove width.
Dicing or the like may be used. However, scribing is most preferable in forming the C-th dividing groove. Further, in the present embodiment, the scribe lines are formed in a lattice shape. However, as shown in FIG. 3, a pair of notches may be formed in the A-th groove to divide the element. FIG.
3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided at the bottom of the A-th split groove. In this case, the total film thickness of the wafer is 150 μm or less, or G
The cutting distance to the back surface of the aN substrate is preferably 150 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is performed in the substrate.

As in the present embodiment, in order to divide the wafer into chips at the locally thinned groove formed by forming the C-th split groove in the A-th split groove, the C-th split groove is formed from the bottom of the C-th split groove. G
It is preferable that the cutting distance to the back surface of the aN substrate is short.
The cutting distance is preferably 200 μm or less, more preferably 150 μm or less, like the thickness of the GaN substrate subjected to chlorine doping. The lower limit of the thickness of the cutting distance is not particularly limited. However, if the thickness is too small, the wafer will be broken during the process for device formation. Therefore, the lower limit of the cutting distance is desirably 50 μm or more.

(Embodiment 5) In Embodiment 5, a C-th split groove is formed in the A-th split groove, and the C-th split groove is formed.
A method of forming a B-th split groove on the opposite side of the split groove and dividing the chip will be described. Here, the crystal growth side is
It refers to the opposite side to the substrate side.

FIG. 7 shows a C-plane (0001) n-type GaN substrate 500, an n-type GaN buffer layer 501, and an n-type Al _x1 Ga
_1-x1 N cladding layer 502, active layer 503, p-type Al _x2
It comprises a Ga _{1 -x2} N cladding layer 504, a p-type GaN contact layer 505, an n-type electrode 506, a p-type electrode 507, an A-th split groove 508, a C-th split groove 509, and a B-th split groove 510. I have. The GaN substrate 500 has a chlorine concentration of 1
× 10 ¹⁶ / cm ³ is doped.

The method of manufacturing the nitride semiconductor light emitting diode of FIG. 7 is the same as that of the first embodiment. The chip division of the wafer on which the nitride semiconductor light emitting diode device is formed will be described.

First, the GaN substrate side of the above-mentioned wafer is polished by a polishing machine to make the thickness of the chlorine-doped GaN substrate 150 μm and mirror-finished. The reason why the GaN substrate surface is mirror-finished (made transparent) is that the formation positions of the split grooves described below can be easily confirmed from the back surface side, and the adjustment of the formation positions of the p-electrode and the n-electrode can be easily performed. To do that. Next, the wafer is etched with a mixed solution of sulfuric acid containing hydrofluoric acid or hot phosphoric acid. This etching treatment is performed to remove surface distortion and oxide film caused by polishing, to reduce the contact resistance of the p-type and n-type electrodes, and to prevent electrode peeling. Then p
(4 nm) / T on the GaN contact layer 505
After a light-transmitting p-type electrode 507 is patterned by lithography in the order of i (3 nm) / Au (1 nm), A
forming a u-pad electrode and introducing a small amount of oxygen,
Annealing was performed at 00 ° C. in an N ₂ atmosphere. As a result, the contact resistance was reduced by forming the p-type electrode. The reason why the pattern of the p-type electrode is formed is to form a B-th split groove described below in a region where the p-electrode is not covered. Next, the wafer was turned over and Mo (15 nm) / Al (150
An n-type electrode 506 is formed by lithography technology. At this time, an n-type electrode pattern is formed directly opposite to the formation position of the p-type electrode pattern on the crystal growth side, and a region where the electrodes are not covered to form a split groove is formed. Match.

The surface on the crystal growth side of the wafer is subjected to a masking process by a lithography technique, and the wafer is set in a reactive ion etching apparatus. By dry etching, a depth of 0.2 on the growth surface along the <1-100> direction.
μm, line width 20 μm, pitch 350 μm, <11-2
0> direction (perpendicular to the direction), the pitch 34
An A-th split groove 508 having a thickness of 5 μm, a depth of 0.1 μm, and a line width of 20 μm was formed. The A-th split groove has an n-type electrode 506.
Is preferably formed in the uncoated portion. This is because it causes electrode peeling.

Next, with a diamond needle of a scriber,
A pitch 350 along the substantially center line of the bottom of the A-th groove.
A scribe is performed once in the <1-100> direction at a depth of 0.1 μm and a line width of 5 μm. Next, in the direction perpendicular to the scribe direction (<11-20> direction), the pitch 3
The scribe is made once along a substantially central line of the bottom of the A-th groove at 45 μm, depth of 0.1 μm, and line width of 5 μm. In this manner, a scribe line is formed so as to form a chip of 350 μm × 345 μm square, and a C-th dividing groove 509 is formed.

Subsequently, an adhesive seal was formed on the crystal growth side of the wafer.
And attached on a scriber table with the crystal growth side down, and fixed with a vacuum chuck. After fixing,
With a diamond needle of a scriber, a pitch of 350 μm is formed on the surface on the GaN substrate side (the surface of the n-type GaN substrate 500).
m, a depth of 5 μm, and a line width of 5 μm are scribed once in the <1-100> direction. Next, in a direction perpendicular to the scribe direction (<11-20> direction), a pitch of 345 μm is set.
scribe once with a depth of 5 μm and a line width of 5 μm. In this way, scribe lines are formed so as to form chips of 350 μm × 345 μm square, and the B-th split groove 510 is formed. However, the formation position of the B-th split groove 510 is set to a position substantially coincident with the C-th split groove 509. Also, it is preferable that the B-th split groove 510 is formed at a position where the electrode is not covered similarly to the A-th split groove 508.

After scribing, release the vacuum chuck, remove the wafer from the table, and lightly press the wafer from the GaN substrate side with a roller to obtain a large number of 350 μm × 345 μm square chips from a 2-inch φ wafer. Obtained. No cracks, chippings, etc. occurred on the cut surface of the chip, and a product with no external defect was taken out.
% Or more.

In the present embodiment, the reason why the chip was divided into a desired shape with a high yield is that a nitride semiconductor film including a light emitting layer was formed on a similar nitride semiconductor substrate doped with chlorine, and By forming the C-th split groove in the A-th split groove without cutting at once, and additionally forming the B-th split groove at a position opposite to the C-th split groove forming position. . This is because it has the features of Embodiment 3 and Embodiment 4 and can be cut into a desired chip shape. The effect of chlorine doping in the nitride semiconductor substrate is the same as in the first embodiment.

In this embodiment, reactive ion etching is used to form the A-th groove. However, the groove may be formed by a physical method such as a half-cut by dicing or a scriber. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in this embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scriber is used for forming the B-th and C-th groove widths. However, the above-described etching method, dicing or the like may be used. However, scribing is most preferable in forming the B-th and C-th split grooves.

In this embodiment, the scribe lines are formed in a lattice shape. However, as shown in FIG. 3, a pair of notches may be formed only at the edge of the wafer to divide the elements. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided in the bottom of the A-th split groove. In this case, the total thickness of the wafer is preferably 150 μm or less, or the cutting distance from the bottom of the B-th groove to the bottom of the C-th groove is preferably 150 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is performed in the substrate.

In this embodiment, the chlorinated GaN substrate is polished to a thickness of about 150 μm. However, as described in the first embodiment, in order to facilitate chip division, the GaN substrate is polished. Is preferably 200 μm or less, more preferably 150 μm or less, and more preferably 50 μm or more. GaN doped with chlorine
As a method of partially thinning the GaN substrate in addition to polishing the entire substrate to make it thinner, the cutting distance between the bottom of the B-th split groove and the bottom of the C-th split groove may be shortened. At this time, the cutting distance is preferably 200 μm or less, more preferably 150 μm or less, and 50 μm or more, similarly to the thickness of the GaN substrate subjected to chlorine doping.

(Embodiment 6) In this embodiment 6, a nitride semiconductor substrate (100 μm in thickness after polishing) which has been subjected to chlorine doping in Embodiment 1 is not subjected to chlorine doping. Embodiment 2 is the same as Embodiment 1 except that the substrate (the thickness after polishing is 80 μm) is changed.

The chip division according to the present embodiment will be described. Here, the crystal growth side refers to the side opposite to the substrate side. The GaN substrate side of the wafer is polished by a polishing machine so that the thickness of the GaN substrate that has not been chlorine doped is 80 μm.

The wafer was dry-etched to a depth of 1 μm, a line width of 10 μm, a pitch of 350 μm, and a pitch of <11− along the <1-100> direction along the crystal growth side.
The A-th groove 108 having a depth of 1 μm, a line width of 10 μm, and a pitch of 330 μm was formed along the 20> direction. Subsequently, the surface on the GaN substrate side was scribed to <1-1.
00> direction, pitch 350 μm, depth 5 μm,
A line width of 5 μm and a pitch of 3 along the <11-20> direction
B-th split groove 1 having a thickness of 30 μm, a depth of 5 μm, and a line width of 5 μm
09 was formed. However, the formation position of the B-th split groove 109 is approximately at the center of the line width of the A-th split groove.
09 match.

After the dicing, the vacuum chuck is released, the wafer is removed from the table, and a large number of chips having a size of 350 μm × 330 μm are obtained from a 2-inch φ wafer by lightly pressing the wafer from the GaN substrate side with a roller. Obtained. Cracks, chipping, etc. did not occur on the cut surface of the chip, and a product having no external defect was taken out.
% Or more.

In the present embodiment, a yield of 85% or more,
The reason why the chip was divided into a desired shape was that a nitride semiconductor film including a light emitting layer was formed on a nitride semiconductor substrate of the same type, and the first and second cleavage grooves were cut without cutting at a time. This is because the bottom of the A-th split groove is formed deeper than the position of the nitride semiconductor light emitting layer, and the B-th split groove is narrower than the A-th split groove width. That is, since both the grown film and the substrate are nitride semiconductors of the same type, they have the same cleavage characteristics, the bottom of the A-th split groove is deeper than the nitride semiconductor light emitting layer position, and the A-th split groove is Since the groove width is wider than that of the B-slot, the cracked line split by the B-slot can be broken at the shortest cutting distance from the bottom of the B-slot to the bottom of the A-slot. Can only reach the crab,
This is because cleavage can be prevented in an unintended direction, and the chip can be cut into a desired chip shape. In addition, A
The bottom of the groove is deeper than the position of the nitride semiconductor light emitting layer. Therefore, even if chipping or cracking occurs during chip division, the light emitting layer is not damaged, and the incidence of element failure is reduced. be able to. Embodiment 1
It is considered that the reason why the yield of the chip is lower than that in the above is that no chlorine doping is performed in the nitride semiconductor substrate. However, the yield is improved by about 10% or more as compared with the related art in which the chip is divided at a time without forming at least two or more split grooves.

In this embodiment, reactive ion etching is used to form the A-th groove. However, the groove may be formed by a physical method such as a half-cut by dicing or a scriber. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in the present embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scribe is used to form the B-th groove width.
Dicing or the like may be used. However, scribing is most preferable in forming the B-th groove. This is because a groove can be formed quickly and with a narrow groove width.

A nitride semiconductor substrate not doped with chlorine is more difficult to split into chips than a nitride semiconductor substrate doped with chlorine, and it is preferable to reduce the thickness of the substrate. According to an experiment conducted by the present inventors, the thickness of the nitride semiconductor substrate not subjected to chlorine doping is 150 μm.
Or less, more preferably 100 μm or less. The lower limit of the thickness of the nitride semiconductor substrate that has not been chlorine-doped is not particularly limited, but if it is too thin, the wafer will break during the process for device fabrication, and the thickness of the nitride semiconductor substrate will be reduced. The lower limit is desirably 50 μm or more. In addition, Ga which is not chlorine-doped
In addition to polishing the entire N substrate to make it thinner, as a method of partially thinning a GaN substrate that has not been chlorine-doped,
The cutting distance between the bottom of the A-th split groove and the bottom of the B-th split groove may be shortened. At this time, the cutting distance is 1 as in the case of the thickness of the GaN substrate not chlorine-doped.
50 μm or less, more preferably 100 μm
Hereinafter, it is 50 μm or more.

In addition, GaN which is not chlorine-doped
As a method of partially thinning a GaN substrate that has not been chlorine-doped in addition to polishing the entire substrate to make it thinner, the cutting distance between the bottom of the A-th groove and the bottom of the B-th groove is shortened. May be. The cutting distance at this time is chlorine chloride.
As with the thickness of the unpinned GaN substrate,
μm or less, more preferably 100 μm or less, and 50 μm or more. In addition to the dividing groove of the present embodiment, a scribe line may be formed in the A-th dividing groove as the C-th dividing groove to divide the chip.

Also, as shown in FIG. 3, a pair of notched grooves are formed on the A-th split groove or on the back surface of the GaN substrate instead of the lattice-shaped split grooves formed by the B-th and C-th scribes to divide the element. You may. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG.
An example in which a pair of notched grooves is provided at the bottom of the A-th split groove is shown. In this case, the total thickness of the wafer is preferably 100 μm or less, or the cutting distance from the bottom of the A-th split groove to the back surface of the GaN substrate is preferably 100 μm or less. However, the total film thickness is a value when no chlorine is doped in the nitride semiconductor substrate.

(Embodiment 7) The present embodiment 7 is directed to a case where the chlorine-doped nitride semiconductor substrate (having a thickness of 200 μm after polishing) of Embodiment 2 is not subjected to chlorine doping. Embodiment 5 is the same as Embodiment 5 except that the substrate (the thickness after polishing is 150 μm) is changed. The chip division according to the present embodiment will be described. Here, the crystal growth side refers to the side opposite to the substrate side. The GaN substrate side of the wafer is polished by a polishing machine so that the thickness of the chlorinated GaN substrate is 150 μm.

The wafer was dry-etched onto the surface on the crystal growth side along the <1-100> direction by dry etching.
Depth 7 μm, line width 20 μm, pitch 350 μm, <1
Along the 1-20> direction, a depth of 7 μm, a line width of 20 μm,
The A-th split groove 208 having a pitch of 340 μm was formed.
Subsequently, the surface on the GaN substrate side was <1
-100> direction, pitch 350μm, depth 5μ
m, a line width of 5 μm, and a B-th groove 209 having a pitch of 340 μm, a depth of 5 μm, and a line width of 5 μm were formed along the <11-20> direction. However, the formation position of the B-th split groove 209 is substantially at the center of the line width of the A-th split groove 208.
Of the groove 209 are aligned.

After scribing, the vacuum chuck is released, the wafer is detached from the table, and the wafer is gently pressed from the crystal growth surface side with a roller, so that a chip of 350 μm × 340 μm square is obtained from the wafer of 2 inch φ. I got a lot. No cracks, chippings, etc. occurred on the cut surface of the chip, and a product with no external defect was taken out.
% Or more. The effect of this embodiment is the same as that of the sixth embodiment.

(Eighth Embodiment) In the eighth embodiment, a nitride semiconductor substrate (150 μm in thickness after polishing) obtained by polishing the chlorine-doped nitride semiconductor substrate of the third embodiment is not subjected to chlorine-doping. The third embodiment is the same as the third embodiment except that the substrate (the thickness after polishing is 100 μm) is changed.

A description will be given of chip division of this embodiment. Here, the crystal growth side refers to the side opposite to the substrate side. The GaN substrate side of the wafer is polished by a polishing machine to make the thickness of the GaN substrate that has not been chlorine-doped 100 μm.

Next, the surface on the crystal growth side of the wafer is subjected to mask processing by lithography, and is set in a reactive ion etching apparatus. By dry etching, a depth of 0.2 μm and a line width of 20 μm were formed on the crystal growth side of the wafer.
m, and the A-th groove 308 having a pitch of 350 μm
The pitch on the substrate side is 350 μm by a scriber.
A B-th split groove 309 having a depth of 5 μm and a line width of 5 μm was formed in a lattice shape. However, the formation position of the B-th split groove 309 is set to a position substantially coincident with the center line of the line width of the A-th split groove 308, and both the crystal growth surface and the GaN substrate surface
The direction of the groove formation is <11-20> with respect to the nitride semiconductor.
Or <1-100> direction.

After scribing, the vacuum chuck was released, the wafer was removed from the table, and the wafer was lightly pressed from the GaN substrate side with a roller to obtain a large number of 350 μm square chips from the 2-inch φ wafer. . Cracks, chipping, etc. did not occur on the cut surface of the chip, and a product having no external defect was taken out. The yield was 82% or more.

In the present embodiment, a yield of 80% or more,
Chips having a desired shape can be divided by forming a nitride semiconductor film including a light-emitting layer on a nitride semiconductor substrate of the same type, and cutting the A-th groove and the B-th groove without cutting at once. This is because the split groove is formed, and the B-th split groove is configured to be narrower than the A-th split groove width. That is, since both the grown film and the substrate are nitride semiconductors of the same type, they have the same cleavage characteristics, that the A-th split groove has a wider groove width than the B-th split groove, and In order to split the broken line by the B-th split groove by the shortest cutting distance by cutting the B-divided groove, it is necessary to cut from the bottom of the B-th split groove somewhere from the bottom of the A-th split groove. , And it can be prevented from being cleaved in an unintended direction and can be cut into a desired chip shape. It is considered that the reason why the chip yield is lower than that in the first embodiment is that chlorine doping is not performed in the nitride semiconductor substrate. However, the yield is improved by about 10% or more as compared with the related art in which the chip is divided at a time without forming at least two or more split grooves.

In this embodiment, reactive ion etching is used to form the A-th groove. However, the groove may be formed by a physical method such as a half-cut by dicing or a scriber. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in this embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, and thermal A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

A nitride semiconductor substrate not doped with chlorine is more difficult to split into chips than a nitride semiconductor substrate doped with chlorine, and it is preferable to reduce the thickness of the substrate.

As described in the sixth embodiment, the thickness of the GaN substrate is preferably 150 μm or less, more preferably 100 μm or less, to facilitate chip division.
μm or more was preferred.

In the present embodiment, the B-th dividing groove is formed in a lattice shape using a scribe. However, as shown in FIG. 3, a pair of notching grooves are formed only at the edge portion of the wafer to divide the element. May be. In this case, the total thickness of the wafer is 10
It is preferable that the cutting distance from the bottom of the A-th groove to the back surface of the GaN substrate is 100 μm or less. However, the total film thickness is a value when no chlorine is doped in the nitride semiconductor substrate.

Ninth Embodiment A ninth embodiment is directed to a nitride semiconductor substrate (130 μm in thickness after polishing) obtained by chlorine-doping the nitride semiconductor substrate of the fourth embodiment. Embodiment 4 is the same as Embodiment 4 except that the substrate is changed to a thickness of 100 μm after polishing. The chip division according to the present embodiment will be described. Here, the crystal growth side refers to the side opposite to the substrate side. The GaN substrate side of the wafer is polished by a polishing machine to make the thickness of the GaN substrate that has not been chlorine-doped 100 μm.

The surface on the crystal growth side of the wafer is subjected to a mask process by lithography, and is set in a reactive ion etching apparatus. By dry etching, the crystal growth side has a depth of 0.2 μm along the <1-100> direction.
m, line width 30 μm, pitch 350 μm, <11-20
The A-th split groove 408 having a depth of 0.2 μm, a line width of 30 μm, and a pitch of 100 μm is formed along the direction. Subsequently, along a substantially central line of the bottom of the A-th groove, the scriber is used to provide a pitch of 350 μm, a depth of 0.1 μm, a line width of 5 μm, and a width of 5 μm along the <1-100> direction.
20> direction, pitch 100μm, depth 0.1μ
m, and a C-th groove 409 having a line width of 5 μm was formed. However, the position where the C-th split groove 409 is formed is a position on the bottom of the A-th split groove 408 that is substantially coincident with the center line of the A-th split groove line width.

After the scribing, the vacuum chuck was released, the wafer was removed from the table, and a small number of chips of 350 μm × 100 μm square were obtained from a 2-inch φ wafer by lightly pressing the wafer from the crystal growth side with a roller. Obtained. No cracks, chippings, etc. occurred on the cut surface of the chip, and a product with no external defects was taken out.
% Or more. In the present embodiment, the reason why the chip can be divided into a desired shape with a yield of 80% or more is that a nitride semiconductor film including a light emitting layer is formed on a similar nitride semiconductor substrate and cut at one time. This is because the A-th split groove and the C-th split groove were formed without forming the C-th split groove in the A-th split groove. In other words, since both the grown film and the substrate are nitride semiconductors of the same type, they have the same cleavage characteristics, and have the C-th split groove formed substantially along the center line at the bottom of the A-th split groove. Since the breaking line broken by the C-th split groove is broken along the portion locally thinned by the A-th split groove, it is prevented from being cleaved in an unintended direction, and cut into a desired chip shape. This is because you can do it. It is considered that the reason why the chip yield is lower than that in the fourth embodiment is that chlorine doping is not performed in the nitride semiconductor substrate.

However, as compared with the conventional method in which chips are divided at once without forming at least two or more split grooves,
The yield is improved by about 10% or more.

In this embodiment, reactive ion etching is used to form the A-th groove. However, the groove may be formed by a physical method such as a half-cut by dicing or a scriber. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in the present embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique. Further, in the present embodiment, the scribe is used to form the C-th split groove width, but the above-described etching method, dicing, or the like may be used. However, scribing is most preferable in forming the C-th dividing groove.

A nitride semiconductor substrate not doped with chlorine is more difficult to split into chips than a nitride semiconductor substrate doped with chlorine, and it is preferable to reduce the thickness of the substrate. According to an experiment conducted by the present inventors, the thickness of the nitride semiconductor substrate not subjected to chlorine doping is 150 μm.
Or less, more preferably 100 μm or less,
0 μm or more.

As in the present embodiment, in order to divide the wafer into chips at the locally thinned groove formed by forming the C-th split groove in the A-th split groove, the bottom of the C-th split groove is used. G
It is preferable that the cutting distance to the aN substrate (back surface) is short. The cutting distance is preferably 150 μm or less, more preferably 100 μm or less, like the thickness of the nitride semiconductor substrate on which chlorine doping is not performed. The lower limit of the thickness of the cutting distance is not particularly limited. However, if the thickness is too small, the wafer will be broken during the process for device formation. Therefore, the lower limit of the cutting distance is desirably 50 μm or more.

Further, GaN without chlorine doping was used.
The substrate is 150 μm thick nitride semiconductor substrate which is easy to cut.
Polished thicker than the bottom of the C-th split groove.
The cutting distance to the N substrate (back surface) may be set to 150 μm or less. As a result, it is difficult to cut the portion other than the split groove portion, and it is possible to prevent cracking and chipping from occurring at the time of chip division.

In the present embodiment, the C-th dividing groove is formed in a lattice shape using scribes. However, as shown in FIG. 3, a pair of notches are formed only at the edge portion of the wafer to divide the element. May be. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided in the bottom of the A-th split groove. In this case, the total thickness of the wafer is 100 μm or less, or
The cutting distance from the bottom of the A-th groove to the back surface of the GaN substrate is preferably 100 μm or less. However, the total film thickness and the cutting distance are thicknesses when chlorine doping is not performed in the substrate.

(Embodiment 10) Embodiment 10
Except that the chlorine-doped nitride semiconductor substrate of Embodiment 5 (thickness after polishing was 150 μm) was changed to a nitride semiconductor substrate without chlorine doping (thickness after polishing 90 μm). Same as in mode 5. The chip division according to the present embodiment will be described. Here, the crystal growth side refers to the side opposite to the substrate side. The GaN substrate side of the wafer is polished by a polishing machine, and chlorine
The thickness of the non-pinged GaN substrate is set to 90 μm.

The surface on the crystal growth side of the wafer is subjected to a mask process by lithography, and is set in a reactive ion etching apparatus. By dry etching, a depth of 0.1 μm is formed along the <1-100> direction on the crystal growth side.
m, line width 20 μm, pitch 400 μm, <11-20
The A-th split groove 508 having a depth of 0.1 μm, a line width of 20 μm, and a pitch of 100 μm was formed along the direction. Subsequently, along a substantially center line on the bottom of the A-th groove, the scriber moves the pitch 40 in the <1-100> direction.
0 μm, depth 0.2 μm, line width 5 μm, <11-20
> Direction, pitch 100μm, depth 0.2μm, line width 5
A μm C-th groove 509 was formed. Further, Ga
On the surface on the N substrate side, along the <1-100> direction, a pitch of 400 μm, a depth of 5 μm, a line width of 5 μm, and <11-20
A B-th groove 510 having a pitch of 100 μm, a depth of 5 μm, and a line width of 5 μm was formed along the direction. However, the formation position of the C-th split groove 509 depends on the position of the A-th split groove 50.
8 is formed at a position substantially coincident with the center line of the line width of the A-th dividing groove, and the forming position of the B-th dividing groove 510 is
It is formed at a position substantially coincident with the C-th split groove 509.

After scribing, release the vacuum chuck, remove the wafer from the table, and lightly press it from the GaN substrate side with a roller to obtain a large number of 400 μm × 100 μm square chips from a 2 inch φ wafer. Obtained. No cracks, chippings, etc. occurred on the cut surface of the chip, and a product with no external defect was taken out.
% Or more.

In the present embodiment, a yield of 85% or more,
The reason why the chip was divided into chips having a desired shape was that a nitride semiconductor film including a light-emitting layer was formed on a nitride semiconductor substrate of the same type, and the C-th split groove was cut into the A-th without cutting at once. This is due to the fact that the groove is formed in the split groove, and in addition, the B-th split groove is formed at a position opposite to the position where the C-th split groove is formed. This has the features of the eighth and ninth embodiments,
This is because it can be cut into a desired chip shape.
It is considered that the reason why the chip yield is lower than that in the third embodiment is that chlorine doping is not performed in the nitride semiconductor substrate. However, at least two
The yield is improved by about 10% or more as compared with the related art in which chips are divided at a time without forming one or more split grooves.

In this embodiment, reactive ion etching is used to form the A-th groove. However, the groove may be formed by a physical method such as half cutting by dicing or scriber. However, the A-th groove is
Since the width of the groove A must be wider than the width of the groove B, formation of the groove A by a scriber is not very preferable. Also, the formation of the A-th dividing groove using dicing is not so preferable because the surface of the nitride semiconductor is easily damaged.

As a chemical groove forming method, in addition to the reactive ion etching introduced in this embodiment, a dry etching method such as a focused ion beam method and an ECR etching method, hydrofluoric acid, hot phosphoric acid, heat A wet etching method using a mixed solution of phosphoric acid and sulfuric acid or the like may be used. By using these etching methods, damage to the nitride semiconductor surface and the groove side surface due to the formation of the groove can be suppressed. Therefore, in this embodiment, dry etching or wet etching Is most preferably used. However, in order to perform the above-described etching, it is necessary to perform a mask process by a lithography technique.

In this embodiment, the scribe is used for forming the B and C-th groove widths. However, the above-described etching method, dicing or the like may be used. However, scribing is most preferable in forming the B-th and C-th split grooves.

The nitride semiconductor substrate not doped with chlorine is more difficult to split into chips than the nitride semiconductor substrate doped with chlorine, and it is preferable to reduce the thickness of the substrate. As described in the sixth embodiment, in order to facilitate chip division, the thickness of the GaN substrate is preferably 150 μm or less, more preferably 100 μm or less, and 50 μm or less.
m or more was preferred.

In addition, GaN which is not chlorine-doped
As a method of partially thinning the GaN substrate other than polishing the entire substrate to make it thinner, the cutting distance between the bottom of the B-th split groove and the bottom of the C-th split groove may be shortened. At this time, the cutting distance is G which is not chlorine-doped.
Similar to the thickness of the aN substrate, the thickness is preferably 150 μm or less,
More preferably, it is 100 μm or less, and 50 μm or more.

In the present embodiment, the B-th and C-th split grooves are formed in a grid pattern using scribes. However, as shown in FIG. 3, a pair of notched grooves are formed instead of the split grooves. The element may be divided. FIG. 3A shows an example in which a pair of notched grooves are provided in an etched portion of a wafer, and FIG. 3B shows an example in which a pair of notched grooves is provided in the bottom of the A-th split groove. In this case, the total thickness of the wafer is 100 μm or less, or
The cutting distance from the bottom of the A-th groove to the GaN substrate (back surface) is preferably 100 μm or less. However,
The total film thickness and the cutting distance are thicknesses when the substrate is not chlorine-doped.

(Embodiment 11) Embodiment 11
A description will be given of the direction in which the groove is formed and the chip shape in the first to tenth embodiments when a C-plane nitride semiconductor substrate is used. However, the directions described below are the directions with respect to the nitride semiconductor.

In consideration of the ease of chip division, the forming direction of the split groove is preferably the <11-20> direction, and then the <1-100> direction. It may be shifted from the above direction by about ± 5 °. A split groove is formed along the <11-20> direction, and an end face formed by splitting is {1-10}.
0 ° plane. In addition, a split groove is formed along the <1-100> direction, and an end face formed by dividing is {11-2}.
0 ° plane.

The chip shapes formed by combining these directions are square, rectangular, equilateral triangle, rhombic,
There are parallelograms, trapezoids, and regular hexagons. It is preferable to divide the chip into the above-described chip shape so that the forming direction of the split groove includes at least the <11-20> direction.

For example, if the forming direction of the split groove is <11-20
In the case of a chip shape of an equilateral triangle, a rhombus, a trapezoid, or a regular hexagon composed only of directions, the direction of chip division is easy, and the yield of chip division is good.

When a rectangle is selected from the above chip shapes, the ratio of the long side L to the short side S of the rectangle is L / S = 1.01
To 4 are preferable. More preferably, the direction of the short side of the rectangle is the <1-100> direction, and the direction of the long side is the <11- direction.
20> direction. This is because <11
In the <-20> direction, a large number of split grooves per unit area are formed, and conversely, <1- <1-
This is because the number of split grooves in the 100> direction is reduced.

In addition, in the case where the direction in which chip division is difficult is formed by forming a groove in the short side and divided in accordance with the above orientation relationship, L / S
Since the ratio is greater than 1, the lever can be used to efficiently apply a force to the dividing groove, which is difficult to divide the chip, and to easily divide the chip. For example, when the L / S ratio is 4, it can be divided by four times the force of normal chip division. The upper limit of the L / S ratio is set to 4 because it is difficult to arrange the chips when packaging them on the stem of the light emitting diode. Therefore, when the purpose is chip division, L / S may be larger than 4.

(Embodiment 12) Embodiment 12 is directed to
A description will be given of the direction in which the groove is formed and the chip shape in Embodiments 1 to 10 when an M-plane nitride semiconductor substrate is used. However, the directions described below are the directions with respect to the nitride semiconductor.

In consideration of the ease of chip division, the forming direction of the dividing groove is preferably in the <0001> direction, and then in the <0001> direction.
2-1-10> direction. It may be shifted from the above direction by about ± 5 °. A split groove is formed along the <0001> direction, and an end face formed by splitting is {2-1-1}.
0 ° plane. Further, a split groove is formed along the <2-1-10> direction, and an end face formed by division is $ 000.
1｝ plane.

The shape of the chip formed by combining these directions includes a square and a rectangle. When a rectangle is selected from the above chip shapes, the ratio of the long side L to the short side S of the rectangle is preferably L / S = 1.01 to 4. More preferably, the direction of the short side of the rectangle is <2-1-10.
> Direction, the direction of the long side is the <0001> direction. This means that a large number of split grooves per unit area are formed in the <0001> direction where chip division is easy, and conversely, the split grooves in the <2-1-10> direction where chip division is difficult compared to the above direction. This is because it is formed less.

In addition, in accordance with the above azimuth relationship, when the direction in which chip division is difficult is formed by forming a groove on the short side, the L / S
Since the ratio is greater than 1, the lever can be used to efficiently apply a force to the dividing groove, which is difficult to divide the chip, and to easily divide the chip. For example, when the L / S ratio is 4, it can be divided by four times the force of normal chip division. The upper limit of the L / S ratio is set to 4 because it is difficult to arrange the chips when packaging them on the stem of the light emitting diode. Therefore, when the purpose is chip division, L / S may be larger than 4.

(Embodiment 13) Embodiment 13
A description will be given of the direction in which the groove is formed and the chip shape in Embodiments 1 to 10 when an R-plane nitride semiconductor substrate is used. However, the directions described below are the directions with respect to the nitride semiconductor.

In consideration of the ease of chip division, the forming direction of the dividing groove is preferably the <0-111> direction, and then the <2-1-10> direction. It may be shifted from the above direction by about ± 5 °. A split groove is formed along the <0-111> direction, and an end face formed by splitting is {2-1}.
10 ° plane. Further, a split groove is formed along the <2-1-10> direction, and an end face formed by splitting is {0-1}.
11 ° plane.

The shapes of the chips formed by combining these directions include a square and a rectangle. When a rectangle is selected from the above chip shapes, the ratio of the long side L to the short side S of the rectangle is preferably L / S = 1.01 to 4. More preferably, the direction of the short side of the rectangle is <2-1-10.
Direction, the direction of the long side is the <0-111> direction. This is because a large number of split grooves per unit area are formed in the <0-111> direction where chip division is easy, and in the <2-1-10> direction where chip division is difficult compared to the above direction. This is for forming a small number of grooves.

In accordance with the above azimuth relationship, when a direction in which chip division is difficult is formed by forming a groove on a short side, L / S
Since the ratio is greater than 1, the lever can be used to efficiently apply a force to the dividing groove, which is difficult to divide the chip, and to easily divide the chip. For example, when the L / S ratio is 4, it can be divided by four times the force of normal chip division. The upper limit of the L / S ratio is set to 4 because it is difficult to arrange the chips when packaging them on the stem of the light emitting diode. Therefore, when the purpose is chip division, L / S may be larger than 4.

(Embodiment 14) Embodiment 14 is directed to
A description will be given of the direction in which the groove is formed and the chip shape in Embodiments 1 to 10 when the A-plane nitride semiconductor substrate is used. However, the directions described below are the directions with respect to the nitride semiconductor.

When the ease of chip division is taken into consideration, the direction in which the groove is formed may be the <0001> direction or the <01- direction.
The direction of 57.6 ° from the 10> direction is preferred, and then <0.
1-10> direction. It may be shifted from the above direction by about ± 5 °. An end face formed by forming a dividing groove along the <0001> direction and dividing the plane is a {01-10} plane. Further, a split groove is formed along the direction of 57.6 ° from the <01-10> direction, and an end face formed by division is as follows:
The {01-12} plane. In addition, a split groove is formed along the <01-10> direction, and an end face formed by division is as follows.
{0001} plane.

The shape of the chip formed by combining these directions includes a square, a rectangle, a triangle, a parallelogram, and a trapezoid. The formation direction of the split groove is at least <0
57.6 from <001> direction or <01-10> direction
It is preferable to divide the chip into the above-mentioned chip shape so as to include the direction of the angle.

When the chip is divided into a triangular shape or a parallelogram shape so as to include a direction of 57.6 ° from the <0001> direction and the <01-10> direction, both of the chip divisions are performed. Since the direction is easy, the yield of chip division is good.

When the chip is divided into parallelograms so as to include the <01-10> direction and the direction at 57.6 ° from the <01-10> direction, the short shape of the parallelogram is reduced. The direction of the side is the <01-10> direction, and the direction of the long side is 57.6 ° from the <01-10> direction. This is 5 minutes from the <01-10> direction where chip division is easy.
In the direction of 7.6 °, a large number of split grooves per unit area are formed.
This is because the number of split grooves in the -10> direction is reduced.

When a rectangle is selected from the above chip shapes, the ratio of the long side L to the short side S of the rectangle is L / S =
1.01 to 4 are preferred. More preferably, the direction of the short side of the rectangle is the <01-10> direction, and the direction of the long side is the <0001> direction. This is because a large number of split grooves per unit area are formed in the <0001> direction where chip division is easy, and conversely, <0> where chip division is difficult compared to the above direction.
This is because the number of split grooves in the 1-10> direction is reduced.

In the case where the direction in which the chip is difficult to divide is formed by forming a groove on the short side in accordance with the azimuthal relationship of the rectangular shape, the L / S ratio is larger than 1, and the principle of leverage is used. A force can be efficiently applied to the dividing groove in which chip division is difficult, and chip division can be facilitated. For example, when the L / S ratio is 4, it can be divided by four times the force of normal chip division. The upper limit of the L / S ratio is set to 4 because it is difficult to arrange the chips when packaging them on the stem of the light emitting diode. Therefore, when the purpose is chip division, L / S may be larger than 4.

(Embodiment 15) In this embodiment, formation of an end face of a nitride semiconductor laser device and chip division will be described. First, the n-type GaN substrate 60
0 will be described.

FIG. 8 shows the seed substrate 10 and the n-type GaN substrate 60.
The n-type GaN substrate 600 is composed of a low-temperature buffer layer 15, an n-type GaN film 20, a dielectric film 30, and a chlorine-doped n-type GaN thick film 40.

The low-temperature buffer layer 15 is laminated on the seed substrate 10 at 550 ° C. by MOCVD. Next, while doping Si at a growth temperature of 1050 ° C., n of 1 μm
A type GaN film 20 is manufactured.

After forming the n-type GaN film 20, the wafer is taken out from the MOCVD apparatus, and the
The dielectric film is formed to a thickness of 100 nm using the D method or the EB evaporation method.
Then, the dielectric film 30 is processed into a periodic stripe pattern by lithography technology. The stripe shape is such that a stripe is formed in the <1-100> direction with respect to the n-type GaN film 20 and the stripe width is 5 μm and the pitch is 1 in the <11-20> direction perpendicular to the direction.
A periodic stripe pattern of 0 μm was formed.

Subsequently, the wafer having the dielectric film 30 processed into the stripe shape was set in an HVPE apparatus, and the growth temperature was 1100 ° C., and the Si concentration was 3 × 10 ¹⁸ / c.
While doping at m ³ and chlorine concentration of 1 × 10 ¹⁷ / cm ³ , a 350 μm chlorine-doped n-type GaN thick film 40 is laminated.

According to the above manufacturing method, the n-type GaN thick film 40
After forming the wafer, the wafer is taken out of the HVPE apparatus, the seed substrate 10 is peeled off with a polishing machine, and the n-type GaN substrate 600
Was prepared. The n-type GaN substrate 600 may or may not include the low-temperature buffer layer 15. Similarly, the n-type GaN substrate 600 may or may not include the dielectric film 30. The seed substrate may be deleted after the nitride semiconductor laser device structure is manufactured.

In the method for manufacturing the n-type GaN substrate 600, the seed substrate is a C-plane sapphire, an M-plane sapphire,
Plane sapphire, R plane sapphire, GaAs, ZnO, M
Any of gO, spinel, and Ge may be used. The low-temperature buffer layer 15 includes a low-temperature GaN buffer layer, a low-temperature AlN buffer layer formed at a growth temperature of 450 ° C. to 600 ° C.,
Low temperature Al _x Ga ₁ -xN buffer layer (0 <x <1), low temperature I
Any of the n _y Ga _1-y N buffer layers (0 <y ≦ 1) may be used. The dielectric film 30 is made of SiO ₂ film, SiN _x film, T
Any of an iO ₂ film and an Al ₂ O ₃ film may be used. n-type Ga
The N film 20 may be an n-type Al _z Ga _{1 -z} N film (0 <z <1). Chlorine-doped n-type GaN thick film 40
Is a chlorine-doped n-type Al _w Ga _{1 -w} N thick film (0
<W ≦ 1). The chlorine concentration may be 1 × 10 ¹⁴ / cm ³ or more as in the above embodiment, and the thickness of the thick film may be 50 μm or more.

In the method of manufacturing the n-type GaN substrate 600, particularly when the seed substrate is Si, the manufacturing is performed as follows.

First, a 1 μm thick n-type AlGaN film 20 is formed on a Si seed substrate 10 (400 μm thick) by MOCVD.
Are stacked and removed from the MOCVD apparatus. However, FIG.
It is better not to stack the low-temperature buffer layer 15 shown in FIG.
According to the findings of the present inventors, the n-type AlGaN
The film 20 must be a nitride semiconductor film grown at a high temperature of at least 1000 ° C. and containing at least Al. Except for the above conditions, the nitride semiconductor did not grow on the Si seed substrate. Next, a dielectric film 30 is formed and processed into a stripe shape by lithography in the same manner as in the above manufacturing method. Subsequently, the wafer is set in an HVPE apparatus, and an n-type GaN thick film 40 is formed while doping chlorine and Si. The chlorine concentration may be 1 × 10 ¹⁴ / cm ³ or more as in the above embodiment, and the thickness of the thick film may be 50 μm or more. The seed substrate requiring the same method as the above manufacturing method is 6H-
They are a SiC seed substrate, a 4H-SiC seed substrate, and a 3C-SiC seed substrate.

Next, a method for manufacturing a nitride semiconductor laser device using the n-type GaN substrate 600 will be described.

FIG. 9 shows a nitride semiconductor laser structure, in which an n-type GaN substrate 600 and an n-type GaN buffer layer 6 are formed.
01, n-type Al _0.1 Ga _0.9 N cladding layer 602, n-type G
aN light guide layer 603, active layer 604, p-type Al _0.2 G
a _0.8 N carrier block layer 605, p-type GaN light guide layer 606, p-type Al _0.1 Ga _0.9 N cladding layer 607,
It is composed of a p-type GaN contact layer 608.

Next, the n-type GaN was placed in a MOCVD apparatus.
The substrate 600 is set, and n-type G is grown at a growth temperature of 1050 ° C.
The aN buffer layer 601 was formed to 1 μm. This n-type Ga
The N buffer layer 601 is formed when the n-type GaN substrate 600 is peeled off from the seed substrate 10.
This layer is provided for the purpose of alleviating the surface distortion, improving the surface morphology and the surface unevenness (flattening), and may be omitted. However, when chlorine is doped into the n-type GaN thick film 40, the surface morphology tends to deteriorate, so that it is preferable to provide the n-type GaN buffer layer 601 as in the present embodiment. . Further, the n-type GaN buffer layer 601 is an n-type Al _x Ga _1-x N buffer layer (0 <
x ≦ 0.3).

Next, a 1 μm thick n-type Al _0.1 Ga _0.9
A N cladding layer 602 is grown. Furthermore, thickness 0.1μ
An n-type GaN light guide layer 603 of m is grown. n-type Ga
After growing the N light guide layer 603, the temperature of the substrate is set to 700 ° C. to 8
The temperature is lowered to about 00 ° C., and a plurality of 4 nm thick In _0.15 Ga
_An active layer 604 (a multiple quantum well structure) composed of a _0.85 N well layer and a 10 nm-thick In _0.02 Ga _0.98 N barrier layer. The active layer of this embodiment forms a barrier layer and a well layer having three periods, Thereafter, a barrier layer is grown.). At this time, doping of Si may or may not be performed. Next, the substrate temperature is raised again to 1050 ° C., and a carrier block layer 605 made of p-type Al _0.2 Ga _0.8 N having a thickness of 20 nm is grown. At this time, Mg may or may not be doped.
In addition, even if the carrier block layer is not provided, no particular trouble occurs.

Thereafter, while doping with Mg, 0.1
A p-type GaN optical guide layer 606 having a thickness of μm is grown.
Further, while doping with Mg, a 0.5 μm thick p
A cladding layer 607 of type Al _0.1 Ga _0.9 N is grown. Finally, a contact layer 608 made of p-type GaN having a thickness of 0.1 μm was grown while doping Mg.

After crystal growth in this manner, MOCV
The inside of the reactor of the D apparatus was changed to total nitrogen carrier gas and NH ₃ , and the temperature was lowered at 60 ° C./min. Substrate temperature is 8
When the temperature reaches 50 ° C., the supply of NH ₃ is stopped and
After waiting at the substrate temperature for a minute, the temperature was lowered to room temperature. The holding temperature of the substrate was preferably between 650 ° C. and 900 ° C., and the standby time was preferably between 3 minutes and 15 minutes. Further, the reaching speed of the temperature drop is preferably 30 ° C./min or more. As a result of evaluating the grown film thus manufactured by Raman measurement, it was found that the p-type characteristics were already exhibited after the growth by the above-described method without performing the conventionally used p-type annealing. . Further, the contact resistance due to the formation of the p-type electrode was also reduced.

SIMS (secondary ion mass spectrosc)
opy) As a result, the residual hydrogen concentration was 3 × 10 ¹⁸ / cm ³ or less near the outermost surface of the p-type GaN contact layer 608. According to an experiment by the inventors, when the substrate temperature was lowered to room temperature in an NH ₃ atmosphere after forming the grown film, the residual hydrogen concentration was high near the outermost surface of the grown film, so that It is considered that the residual hydrogen concentration is caused by the NH ₃ atmosphere after the growth is completed. It is known that this residual hydrogen prevents activation of Mg which is a p-type impurity. The residual hydrogen concentration is 5 × 10 ¹⁹ / cm ³
The following is preferred.

After the growth of the p-type GaN contact layer 608, the carrier gas is replaced with N ₂ , the supply of NH ₃ is stopped, and the growth temperature is maintained for a predetermined time, thereby promoting the p-type GaN contact layer 608. As a result, the residual hydrogen concentration near the outermost surface of the grown film was reduced, and the contact resistance was reduced. As a method of further reducing the contact resistance due to the formation of the p-type electrode,
Preferably, the vicinity of the outermost surface of the growth film (the outermost surface of the p-type layer) is removed by etching, and a p-type electrode is formed on the removed surface. The layer thickness for removing the outermost surface of the grown film (the outermost surface of the p-type layer) is 10
nm or more, and there is no particular upper limit, but it is preferable that the residual hydrogen concentration in the vicinity of the removed surface be 5 × 10 ¹⁹ / cm ³ or less.

Although the active layer 604 of the present embodiment has a multiple quantum well structure having three periods, it may have another periodic structure or a single quantum well structure having only a well layer.
The active layer may be made of In _y Ga _1-y N (0 <y ≦ 1), and the In composition may be changed according to a desired laser oscillation wavelength.

It is preferable that the p-type impurity concentration of the p-type GaN contact layer 608 be increased toward the formation position of the p-type electrode. This reduces the contact resistance due to the formation of the p-type electrode. Further, in order to remove residual hydrogen in the p-layer which prevents activation of Mg which is a p-type impurity, a trace amount of oxygen may be mixed during growth of the p-type layer.

Hereinafter, chip division of a wafer on which the nitride semiconductor laser device is formed will be described with reference to FIGS. Here, the crystal growth side refers to the side opposite to the substrate side.

First, the GaN substrate side of the above-mentioned wafer is polished by a polishing machine to make the thickness of the chlorin-doped GaN substrate 100 μm and mirror-finished. Next, the wafer is etched with a mixed solution of sulfuric acid containing hydrofluoric acid or hot phosphoric acid. This etching process
Removal of surface distortion and oxide film caused by polishing, p
This is performed to reduce the contact resistance of the mold and n-type electrodes and to prevent electrode peeling.

Next, the crystal growth surface of the wafer is subjected to mask processing by lithography technology, and is set in a reactive ion etching apparatus. P-type A by dry etching
drill down to l _{0. 1} Ga _0.9 N cladding layer 607 to the front of the p-type GaN optical guide layer 606, to form a ridge stripe structure (ridge 620), a refractive index waveguide Le - Zadaio - making de . At this time, the A1th split groove 612
Are simultaneously formed along the <1-100> direction. The stripe direction of the ridge is <1-100> of the nitride semiconductor.
(FIG. 12A).

Next, an SiO ₂ insulating film 609 is deposited to expose the outermost surface of the p-type GaN contact layer 608 in the ridge portion 620, and to cover the exposed portion (2 μm width) of Pd (10 nm) / Mo (10 nm) / Au (15
0 nm) are sequentially deposited, and a p-type electrode 610 is formed in a pattern by lithography. After the formation of the p-type electrode 610, N _{2 at} 450 ° C. was introduced while introducing a small amount of oxygen.
Annealing was performed in an atmosphere. As a result, the contact resistance was reduced by forming the p-type electrode.

Next, as in the second embodiment, the bottom of the split groove is located below the interface position between the nitride semiconductor film and the GaN substrate on the crystal growth side surface by using the reactive ion etching method. As described above, the depth is 8 μm, the line width is 10 μm, and the pitch is 5 μm.
12 μm A2 split grooves 614 were formed (FIG. 12).
(a)). The A2 split groove is formed along the <11-20> direction perpendicular to the ridge stripe direction.

Subsequently, the wafer was turned over and the GaN
An n-type electrode 611 of Ti (15 nm) / Al (150 nm) is formed on the substrate side by lithography. The pattern is formed by the A-th order from the GaN substrate side.
This is for confirming the formation positions of the first split groove 612 and the A2th split groove 614.

Next, an adhesive sheet is stuck on the surface on the crystal growth side, stuck on the scriber table with the GaN substrate side up, and fixed with a vacuum chuck. After the fixing, the diamond needle of the scriber has a depth of 5 μm and a line width of 5 μm so that the center of the line width of the A1 split groove 612 substantially coincides.
The substrate is scribed once in the <1-100> direction under the conditions of m and a pitch of 300 μm to form a B1 split groove 613 (FIG. 12B). Subsequently, in a direction perpendicular to the B1 split groove 613 (<11-20> direction), the depth is 5 μm and the line width is 5 μm.
A single scribing is performed under the conditions of m and a pitch of 510 μm to form a B2th split groove 615 (FIG. 12B).

After scribing, the vacuum chuck is released, the wafer is removed from the table, the chip is lightly divided along the B2 split groove 615 from the GaN substrate side by a breaking device, and the laser element is etched. (FIG. 10). Subsequently, chip division is performed in the same manner as described above along the direction of the B1 split groove 613 (FIG. 11).

In this manner, a large number of laser element chips were obtained from a 2-inch φ wafer. Cracks, chippings, etc., did not occur on the mirror end face or cut surface of the chip, and when a product having no external defect was taken out, the yield was 95% or more.

[0210] The effects obtained in this embodiment are the same as those in the above-described embodiment.

When the mirror end face of the laser element is formed by etching, the formation of the mirror end face and the formation of the split groove for chip division can be simultaneously formed as in this embodiment. For the laser element chip division other than this embodiment, any one of the first to tenth embodiments may be used. In the present embodiment, an n-type layer,
Although the crystal is grown in the order of the light-emitting layer and the p-type layer, the crystal may be grown in the order of the p-type layer, the light-emitting layer, and the n-type layer. As described above, the formation of the mirror end face and the chip division of the nitride semiconductor laser element can be obtained with a high yield.

[0212]

According to the present invention, when a nitride semiconductor wafer including a light emitting active layer having a nitride semiconductor substrate as a substrate is divided into chips, the occurrence of cracks and chipping at cut surfaces and interfaces can be prevented, and It is possible to obtain a nitride semiconductor chip having excellent light emitting performance without impairing crystallinity and to cut into a desired shape and size with a good yield.

[Brief description of the drawings]

FIG. 1 is a view showing formation of a dividing groove for chip division shown in the first embodiment.

FIG. 2 is a diagram illustrating formation of an A-th split groove (substrate side) shown in the first embodiment.

FIG. 3 is an example of formation of a notched groove shown in the first embodiment.

FIG. 4 is a view showing formation of a dividing groove for chip division shown in the second embodiment.

FIG. 5 is a diagram of forming a split groove for chip division shown in the third embodiment.

FIG. 6 is a view showing formation of a dividing groove for chip division shown in the fourth embodiment.

FIG. 7 is a view showing formation of a dividing groove for chip division shown in the fifth embodiment.

FIG. 8 is a view illustrating a method for manufacturing the n-type GaN substrate described in the fifteenth embodiment.

FIG. 9 is a configuration diagram of the nitride semiconductor laser shown in the fifteenth embodiment.

FIG. 10 is a {1-100} cross-sectional view of the nitride semiconductor laser chip shown in the fifteenth embodiment.

FIG. 11 is a {11-20} cross-sectional view of the nitride semiconductor laser chip shown in the fifteenth embodiment;

FIG. 12 is a front view and a back view of a wafer of the nitride semiconductor laser shown in the fifteenth embodiment.

DESCRIPTION OF SYMBOLS 10 type substrate 15 low temperature buffer layer 20 n-type GaN film 30 dielectric film 40 n-type GaN thick film with chlorine doping 50 above dielectric mask opening 51 above dielectric mask 100, 200, 300 , 400, 500, 600 n
Type GaN substrate 101, 201, 301, 401, 501, 601 n
-Type GaN buffer layer 102, 202, 302, 402, 502, n-type Al
_x1 Ga _1-x1 N cladding layer 103,203,303,403,503,604 active layer 104,204,304,404,504, p-type Al
_{x2Ga1 -x2N} cladding layers 105, 205, 305, 405, 505, p-type Ga
N contact layers 106, 206, 306, 406, 506, 611 n
Mold electrode 107, 207, 307, 407, 507, 610p
Mold electrode 108, 208, 308, 408, 508, A-th split groove 109, 209, 307, 510, B-th split groove 409, 509 C-th split groove 602 n-type Al _0.1 Ga _0.9 N cladding layer 603 n -Type GaN optical guide layer 605 p-type Al _0.2 Ga _0.8 N carrier block layer 606 p-type GaN optical guide layer 607 p-type Al _0.1 Ga _0.9 N cladding layer 608 p-type GaN contact layer 609 SiO ₂ insulating film 612 A1 split groove 613 B1 split groove 614 A2 split groove 615 B2 split groove 620 Ridge part

 ──────────────────────────────────────────────────の Continued on the front page F term (reference) 5F041 AA41 CA04 CA05 CA34 CA40 CA74 CA76 5F073 AA73 AA74 CA07 DA22 DA25 DA34

Claims (11)

[Claims] 1. A method for manufacturing a nitride semiconductor chip from a wafer on which a nitride semiconductor layer having a multilayer structure having an active layer sandwiched between a p-type layer and an n-type layer is crystal-grown on a nitride semiconductor substrate. In the above, a step of forming an A-th split groove on a crystal growth surface of the wafer and a step of forming a split groove at a position corresponding to the A-th split groove and narrower than the A-th split groove width And dividing the semiconductor chip along the split groove. 2. The method according to claim 1, wherein the step of forming the narrow split groove is a step of forming a B-th split groove on a substrate surface of the wafer at a position corresponding to the A-th split groove. Item 3. The method for manufacturing a nitride semiconductor chip according to Item 1. 3. The step of forming the narrow split groove is a step of forming a C-th split groove in the bottom of the A-th split groove at a position coinciding with the A-th split groove. The method for manufacturing a nitride semiconductor chip according to claim 1. 4. The method for manufacturing a nitride semiconductor chip according to claim 2, wherein the A-th groove is formed deeper than the active layer position from the crystal growth surface side. 5. The nitride semiconductor chip according to claim 1, wherein a pair of notches are formed at a bottom of said A-th groove or at an edge of said wafer. Manufacturing method. 6. The method for manufacturing a nitride semiconductor chip according to claim 1, wherein said nitride semiconductor substrate contains at least chlorine. 7. The concentration of chlorine contained is 1 × 10 ¹⁴ /
The method for producing a nitride semiconductor chip according to claim 6, wherein the diameter is cm ³ . 8. The method according to claim 8, wherein the direction of the dividing groove is a nitride semiconductor.
11-20> direction, <1-100> direction, <0001>
Direction, <0-111> direction, 5 from <01-10> direction
The method for manufacturing a nitride semiconductor chip according to any one of claims 1 to 7, wherein the direction is any of 7.6 °. 9. When the shape of the nitride semiconductor chip is a rectangle and the long side of the rectangle is L and the short side is S,
= <11-20> direction, S = <1-100> direction, L =
<0001> direction, S = <2-1-10> direction, L = <
01 => 10 direction, S = <2-1-10> direction, L = <
The method for manufacturing a nitride semiconductor chip according to any one of claims 1 to 8, wherein the 0001> direction is any one of S = <01-10> directions. 10. The manufacture of a nitride semiconductor chip according to claim 9, wherein a ratio (L / S) of a long side and a short side of the nitride semiconductor chip is 1.01 or more and 4 or less. Method. 11. The method for manufacturing a nitride semiconductor chip according to claim 1, wherein said nitride semiconductor substrate is a GaN substrate.