JP4639520B2 - Manufacturing method of nitride semiconductor chip - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor chip made of a nitride semiconductor and a manufacturing method thereof, and more particularly to a nitride semiconductor chip used for a light emitting element such as a light emitting diode or a semiconductor laser and a manufacturing method thereof.
[0002]
[Prior art]
In general, a light emitting element such as a light emitting diode or a semiconductor laser is composed of a semiconductor chip serving as a light source. As materials of these semiconductor chips, for example, GaAs, AlGaAs, GaP, AlGaInP, AlGaInN and the like are used for red, yellow, and green, and AlGaInN, SiC, ZnSe, and the like are used for blue.
[0003]
Such a semiconductor chip is cut using a dicer (dicing saw) with a diamond blade to make a groove on the semiconductor wafer according to the shape of the chip, and then cut and separated into chips by an external force. can get. In addition, using a scriber as well as a dicer, the reciprocating linear motion of the diamond needle similarly draws the ruled line on the semiconductor wafer according to the shape of the chip, and then cuts and separates it into chips by an external force. can get.
[0004]
For example, since the (001) plane of a substrate made of a zinc blende structure crystal such as GaAs or GaP is cleaved in the <110> direction, a square or rectangular chip is obtained by scribing in this direction. Can be easily separated and a beautiful chip cross section without cracks or chips can be obtained.
[0005]
However, in the case of a nitride semiconductor such as AlGaInN, rhombohedral sapphire, hexagonal SiC and GaN are used as the substrate, and in addition to the extremely high hardness of these substrates, the main surface of the substrate In the above, since the angle formed by any two cleavage planes orthogonal to the main surface is different from the right angle, it cannot be separated into square or rectangular chips using only the cleavage plane of the substrate. Therefore, even if dicing or scribing in a direction other than the cleaving direction forcibly with respect to the wafer, the wafer is cracked or chipped before the chip separation, and the wafer with the nitride semiconductor laminated on the substrate is well chipped. It was difficult to separate them.
[0006]
However, in recent years, on the main surface, it has been devised to successfully separate into rectangular or square chips even on a substrate in which an angle between any two cleavage planes orthogonal to the main surface is different from a right angle. . In the following, three conventional techniques for these chip separation methods are shown.
[0007]
The first conventional technique is disclosed in JP-A-5-315646.
[0008]
This is because when a nitride semiconductor wafer on a sapphire substrate is cut, a dicing process for cutting a groove deeper than the thickness of the nitride semiconductor with a dicer from above the nitride semiconductor, and the thickness of the sapphire substrate is reduced by polishing. A polishing step, a step of scribing with a scriber from above the groove formed in the dicing step, and a chip separation step of separating the wafer into chips by pressing the wafer along the scribe line. According to this method, it is shown that cracks and chipping on the cut surface of the wafer can be prevented and the wafer can be cut into a desired shape and size without reducing the crystallinity of the nitride semiconductor.
[0009]
The second prior art is disclosed in Japanese Patent Laid-Open No. 10-125958.
[0010]
This is because when the nitride semiconductor wafer on the sapphire substrate is cut, a step of forming the first split groove in a linear shape from the nitride semiconductor layer side and a line of the first split groove from the sapphire substrate side of the wafer A step of forming a second split groove with a line width narrower than the line width of the first split groove, and a roller along the first split groove and the second split groove. A chip separation step of separating into chips by pressing. This method shows that even a substrate that does not have a cleavage property can be accurately cut with a good yield by using a technique such as scribing, dicing, or laser cutting, and productivity is improved.
[0011]
A third conventional technique is disclosed in Japanese Patent Laid-Open No. 10-256193.
[0012]
This is a method that can be applied not only to the sapphire substrate shown in the first conventional technique and the second conventional technique, but also to a SiC substrate, a GaN substrate, etc. The method comprises a step of depositing a coating layer of a dielectric material or other non-ductile material on the substrate, a step of drawing a ruled line on the substrate, and a step of breaking the substrate along the ruled line. In this method, clean break propagation can be performed up to the substrate, so that it is possible to extend the life of the blade used for the chip break as compared with the case where the substrate is directly divided by scribing or dicing. It is shown that the split groove width can be narrowed.
[0013]
By such a method, even a nitride semiconductor wafer using a substrate having a high hardness and an angle between any two cleavage planes orthogonal to the main surface different from a right angle can be formed into a rectangular or square chip. Became.
[0014]
[Problems to be solved by the invention]
However, even when the nitride semiconductor wafer chip separation method described above is used, the following problems occur.
[0015]
In the methods disclosed in the first conventional technique and the second conventional technique, a split groove is formed on the nitride semiconductor side and / or the substrate side of the wafer in order to obtain rectangular or square chips.
[0016]
However, when these methods are used, it is not possible to separate the chips simply by forming the dividing grooves. Therefore, it is necessary to hold the wafer with a roller to divide it, or scribe from the dividing groove and then divide with a chip breaker or the like. There is.
[0017]
As described above, even if any of the above methods is used, an external force is applied to the wafer at the time of chip separation, so that chip breakage or chipping occurs, chip yield decreases, and chip size can be reduced. It becomes difficult.
[0018]
In the method disclosed in the third prior art, the chip is formed by breaking propagation of the ruled line, but the waste is reduced by the width of the dividing groove. In many cases, the chip shape is not only irregular, but also the chip shape is irregular, and the chip is cracked and chipped, resulting in a decrease in chip yield as in the first and second conventional techniques, It becomes difficult to reduce the chip size.
[0019]
Also, in the case of the first to third conventional chip separation methods, in order to finally divide the wafer by external force as described above, in order to suppress cracks and chipping of the chip cross-section during chip separation, Although it is desirable to polish and thin, a thin wafer is liable to be cracked or chipped in the cleavage direction of the substrate during scribing or dicing, and the yield of the chip is conversely reduced.
[0020]
Accordingly, an object of the present invention is to provide a method of manufacturing a nitride semiconductor chip that can improve the yield and reduce the size of the chip while suppressing the occurrence of chip cracking and chipping during chip separation.
[0021]
[Means for Solving the Problems]
In order to solve the above problems, the inventor can suppress chip cracking and chipping in chip separation by attaching a wafer to a reinforcing plate and firmly fixing and scribing in a nitride semiconductor chip manufacturing method. I found.
[0022]
That is, the present invention relates to a method of manufacturing a nitride semiconductor chip that separates a wafer in which a nitride semiconductor is laminated on the main surface of the substrate 1 into chips. The wafer is divided into chips only by scribing with the main surface attached (fixed), and the chip is finally peeled off from the reinforcing plate. There is no process.
[0023]
According to this method, even a wafer such as a hexagonal crystal that is difficult to separate chips can be divided into high-yield square or rectangular chips and small-sized chips, and the manufacturing process can be simplified.
[0024]
DETAILED DESCRIPTION OF THE INVENTION
First application The present invention relates to a method of manufacturing a nitride semiconductor chip in which a wafer having a nitride semiconductor element structure formed on a main surface of a substrate is separated into chips, and the wafer is bonded to the main surface of a reinforcing plate with an adhesive. Either adhesive or adhesive Paste with A method of manufacturing a nitride semiconductor chip comprising: a step of attaching, a step of dividing the wafer into chips by scribing, and a step of peeling the chip from the reinforcing plate. Therefore, the chip can be separated into a desired shape with a high yield and a small size.
[0025]
Second application The present invention relates to a method of manufacturing a nitride semiconductor chip in which a wafer having a nitride semiconductor device structure formed on the main surface of a substrate is separated into chips, and the wafer is bonded to both surfaces of the main surface of the reinforcing plate. A process of pasting through a sheet having at least one property of adhesiveness, adhesiveness, and adhesiveness, a process of dividing the wafer into chips only by scribing, and a process of peeling the chips from the sheet A nitride semiconductor chip manufacturing method characterized in that chip cracking and chipping can be reduced, so that the chip can be separated into a desired shape with a high yield and a small size, and further the chip cleaning. This has the effect of eliminating the need for a process.
[0026]
Third application According to the invention, the wafer is adjusted in advance to a thickness of 50 to 200 μm. Nitride semiconductor chip This method has the effect of further reducing chip cracks and chips.
[0027]
Application No. 4 According to the invention, in the step of attaching the wafer on the main surface of the reinforcing plate, the surface of the wafer on which the nitride semiconductor element structure is formed is attached. Nitride semiconductor chip This method has the effect of eliminating physical damage to the nitride semiconductor device structure when the wafer is scribed, and eliminating the deterioration of crystallinity of the nitride semiconductor device structure.
[0028]
Application No. 5 The present invention is a method for manufacturing a nitride semiconductor chip that separates a wafer having a nitride semiconductor element structure formed on a main surface of a substrate into chips, the side of the wafer having the nitride semiconductor element structure formed thereon, From the jig, the process of affixing to the polishing jig with an adhesive, the process of polishing the substrate side of the wafer, the process of dividing the wafer into chips with only the scribe while the wafer is bonded to the jig, A method of manufacturing a nitride semiconductor chip, comprising: a step of peeling off the chip, and after polishing the wafer, by using a polishing jig as a reinforcing plate, the work of replacing the wafer can be omitted. At the same time, since the cracks and chips of the chip can be reduced, the chip can be separated into a desired shape with a high yield and a small size.
[0029]
Application No. 6 In the invention, the wafer is polished to a thickness of 50 to 200 μm in the polishing process. Nitride semiconductor chip This method has the effect of further reducing chip cracks and chips.
[0030]
Application No. 7 According to the present invention, the angle between any two cleavage planes orthogonal to the main surface is different from a right angle on the main surface. Nitride semiconductor chip Even in the case of using a substrate that is difficult to separate with conventional technology, chip cracking and chipping can be reduced, so that the chip can be separated with a high yield. Have.
[0031]
Application No. 8 The invention is that the substrate is made of sapphire Nitride semiconductor chip In the scriber of a wafer in which a nitride semiconductor device structure is formed on a substrate made of sapphire, chip cracking and chipping can be reduced, so that a desired shape can be obtained with a high yield and a small size. The chip can be separated.
[0032]
Application No. 9 In the invention, the substrate is made of hexagonal SiC. Nitride semiconductor chip This method can reduce chip cracking and chipping in wafer scribes in which a nitride semiconductor element structure is formed on a hexagonal SiC substrate, so it is desirable to achieve a high yield and a small size. The chip can be separated into the shape of
[0033]
Application No. 10 According to the present invention, the substrate is made of a hexagonal nitride semiconductor. Nitride semiconductor chip In the scriber of a wafer in which a nitride semiconductor device structure is formed on a substrate made of a hexagonal nitride semiconductor, chip cracking and chipping can be reduced, so that the yield is high and the size is small. Thus, the chip can be separated into a desired shape.
[0034]
Application No. 11 In the invention of the present invention, the substrate is made of hexagonal GaN. Nitride semiconductor chip This method can reduce chip cracking and chipping in wafer scribes in which a nitride semiconductor element structure is formed on a hexagonal GaN substrate, so it is desirable to achieve high yield and small size. The chip can be separated into the shape of
[0035]
Application No. 12 In the present invention, the substrate is made of a cubic semiconductor, and the (111) plane is the principal surface Nitride semiconductor chip In the scribing of a wafer made of a cubic semiconductor and having a nitride semiconductor element structure formed on a substrate having a (111) plane as a principal surface, chip cracking and chipping can be reduced. The chip can be separated into a desired shape with a high yield and a small size.
[0036]
Application No. 13 According to the present invention, the scribe direction is a first direction that coincides with the cleavage direction of the substrate and a second direction that is orthogonal to the first direction. Nitride semiconductor chip This method has the effect of further reducing chip cracking and chipping during wafer scribing.
[0037]
Application No. 14 of The invention relates to a nitride semiconductor chip The unevenness (roughness) of the divided surface formed by scribing is caused by scribing in the second direction rather than the divided surface formed by scribing in the first direction. The nitride semiconductor chip is characterized in that the formed divided surface is rougher, and light is extracted from two divided surfaces 1 and 2 that face each other among the four chip divided surfaces in the quadrilateral chip. The efficiency is higher than that of the other two divided surfaces 3 and 4.
[0038]
Application No. 15 The invention includes a substrate, an n layer provided on the substrate, a light emitting layer provided on the n layer, a p layer provided on the light emitting layer, the n layer and the p A nitride semiconductor chip using a nitride semiconductor material for each of the n layer, the light emitting layer, and the p layer, each of which is adjacent to a main surface on which each layer is formed. The nitride semiconductor chip is characterized in that the surface roughness of the first pair of side surfaces facing each other is different from the surface roughness of the second pair of side surfaces facing each other. Since it is possible to measure the property by the surface roughness, the orientation of the element can be easily understood at the time of mounting or manufacturing, so that the mounting property and productivity are improved.
[0039]
Hereinafter, an embodiment of the present invention will be described with reference to FIG. In addition, in this drawing, the same code | symbol is attached | subjected to the same member.
[0040]
FIG. 1 is a diagram showing a method for manufacturing a nitride semiconductor chip according to an embodiment of the present invention.
[0041]
In FIG. 1, A- (1) and A- (2) are views showing the main surface of the wafer on which the nitride semiconductor element structure is formed, and A- (3) to (5) are nitride semiconductors on the wafer. FIGS. B- (1) to B- (3) and B- (5) are wafers in the a1 direction shown in A- (1), in which the element structure side is attached to the main surface of the reinforcing plate 2. B- (4) is an enlarged sectional view of the wafer in the a2 direction (a2 direction is perpendicular to the a1 direction) shown in A- (1).
[0042]
First, as shown in B- (1), an n-type nitride semiconductor layer (hereinafter abbreviated as “n layer”) 4, an active layer 5, and a p-type nitride semiconductor layer (hereinafter referred to as “n-type nitride semiconductor layer”) are formed on a substrate 1. (Abbreviated as “p layer”). A wafer in which 6 are sequentially stacked is prepared.
[0043]
Next, as shown in B- (2), in order to form the n-electrode 8 on the n-layer 4, the p-layer 6 is activated by using dry etching or wet etching by RIE (reactive ion etching apparatus). Layer 5 and part of n layer 4 are etched to expose part of the surface of n layer 4. Then, using photolithography and vapor deposition, a p-electrode 7 is formed on the p-layer 6 and an n-electrode 8 is formed on the n-layer 4 exposed by etching to form a nitride semiconductor device structure.
[0044]
When an n-type conductive substrate is used as the substrate 1, the n electrode 8 is not necessarily formed on the n layer 4, but is formed on the substrate 1 on the opposite side of the surface on which the nitride semiconductor layers are stacked. Also good.
[0045]
Next, as shown in A- (3) and B- (3), the wafer on which the electrodes are formed is attached to the reinforcing plate 2 with the side on which the nitride semiconductor element structure is formed as the bonding surface.
[0046]
Here, the reinforcing plate 2 is preferably hard and has a high degree of flatness. However, the reinforcing plate 2 should be hard enough not to be broken by an impact or the like when scribing the wafer, and can be confirmed to have flatness on a visual level. For example, a readily available glass substrate or Si substrate can be used.
[0047]
The adhesive 3 for attaching the wafer to the reinforcing plate 2 is not particularly limited, but is preferably made of a material that is easily softened by heating or a material that is easily dissolved in an organic solvent. It is desirable to use the wax or photoresist used. In addition, the same effect can be acquired even if it uses an adhesive and a sticking agent instead of the adhesive agent 3. FIG.
[0048]
On the other hand, a double-sided PSA sheet having adhesiveness on both sides can be used instead of the adhesive 3. The double-sided pressure-sensitive adhesive sheet is not particularly limited, but by using a double-sided pressure-sensitive adhesive sheet provided on one or both sides with a pressure-sensitive adhesive material that easily loses its adhesiveness upon heating or ultraviolet irradiation, heating or ultraviolet irradiation is performed after chip separation. Thus, the chip can be easily peeled off from the double-sided pressure-sensitive adhesive sheet. Furthermore, if the sheet can be expanded, it is possible to save the trouble of attaching the chip to the semiconductor sheet when the chip is mounted. In addition, you may use a double-sided adhesive sheet and a double-sided adhesive sheet instead of a double-sided adhesive sheet.
[0049]
When the wafer is attached to the reinforcing plate with the adhesive or the double-sided pressure-sensitive adhesive sheet, the wafer may be attached to the reinforcing plate 2 with the same thickness, but the substrate side of the wafer is 200 μm or less in advance. Polishing to a thickness can reduce the number of scribes at the time of chip division, and at the same time can further reduce chip cracks and chipping at the time of scribe.
[0050]
However, when the wafer thickness is less than 50 μm, the wafer is greatly warped by stress, and is easily broken when the wafer is attached to the reinforcing plate 2. Therefore, the wafer thickness is preferably 50 to 200 μm.
[0051]
The surface of the wafer to be bonded can be the bonding surface on the substrate 1 side of the wafer, but it is preferable that the side of the wafer on which the nitride semiconductor element structure is formed is the bonding surface. In this case, the substrate of the wafer Since one side is scribed, crystallinity deterioration of the nitride semiconductor device structure can be reduced. Furthermore, in this case, before attaching the wafer to the reinforcing plate 2, by forming a groove by half-cutting with a dicer from the side where the nitride semiconductor element structure of the wafer is formed at a position matching the scribe line, Crystalline deterioration of the nitride semiconductor device structure can be further reduced.
[0052]
In this way, the reinforcing plate 2 to which the wafer is bonded is attached to the stage of the scriber, or is adsorbed and fixed, and then a diamond needle is used to turn the reinforcing plate 2 into B- (4) and B- (5) in FIG. As shown, scribe at a position between chips.
[0053]
First, as shown in A- (4) in FIG. 1, the wafer is divided into bars by scribing in one direction (a1 direction), and then, as shown in A- (5) in FIG. In addition, the bar is divided into chips by scribing in a direction (a2 direction) orthogonal to the scribe line.
[0054]
The number of scribing in one scribing line can be appropriately adjusted to the number of times the wafer is completely divided along the scribing line, and is about 1 to 10 times, although it varies depending on the material and thickness of the substrate 1. If it carries out like this, the wafer has already cracked according to the scribed ruled line in the state which adhered to the reinforcement board 2 at the time of scribing.
[0055]
After scribing, before the chip is peeled off the reinforcing plate 2, it is preferable to remove the chips generated by the scribing by blowing off with an air gun. In this embodiment, productivity is improved in a single process by using only scribe. However, other methods such as scribe and laser gazette may be combined.
[0056]
Next, regarding the process of peeling off the chips adhering to the reinforcing plate 2, when an adhesive is used for attaching the wafer, the adhesive is dissolved by immersing the reinforcing plate 2 to which the chips are bonded in an organic solvent. By doing so, the chip can be easily peeled off from the reinforcing plate 2.
[0057]
When a double-sided pressure-sensitive adhesive sheet is used for attaching the wafer, the chip can be peeled off from the sheet while the double-sided pressure-sensitive adhesive sheet is attached to the reinforcing plate 2, or the sheet is peeled off from the reinforcing plate 2 in advance. The chip can also be peeled off.
[0058]
When peeling the chip from the adhesive side of the sheet, the chip is easily peeled off from the sheet by heating the double-sided pressure-sensitive adhesive sheet by first bonding the wafer with an adhesive material that loses its adhesiveness when heated. Can do.
[0059]
Further, if the double-sided PSA sheet is a sheet that can be expanded, it can also be used for chip mounting as it is.
[0060]
By the way, in the above description, it has been shown that polishing the wafer substrate 1 can reduce chip cracking and chipping. However, when polishing the wafer, an adhesive is applied to the jig for attaching the substrate with good flatness. If the polishing jig can be installed on the scriber for pasting, the polishing jig can be used in place of the reinforcing plate 2 as it is.
[0061]
For that purpose, it is only necessary to produce a polishing jig having both surfaces that are both flat and thin.
[0062]
Thus, by using the above-described polishing jig, it is possible to save time and effort for attaching the wafer, so that a series of chip separation steps can be shortened, and chip cracks and chips can be reduced.
[0063]
Further, even when polishing is performed using the polishing jig thus improved, chip cracks and chips can be further reduced by setting the substrate thickness to 50 to 200 μm.
[0064]
In the present invention, the substrate 1 is not particularly limited as long as a nitride semiconductor can be grown. A hexagonal substrate such as sapphire, SiC, or GaN, or a cubic substrate such as Si or GaAs may be used. In particular, when the main surface of the substrate 1 is a hexagonal (0001) plane or a cubic (111) plane, the effect of the present invention is remarkable.
[0065]
In the case of using the hexagonal (0001) plane and the cubic (111) plane as the principal plane, the angle between any two cleavage planes orthogonal to the principal plane on the principal plane is different from a right angle. For this reason, when trying to divide the chip into squares or rectangles, it is necessary to divide the chip in at least one direction different from the cleavage plane, which is difficult to break, but since the wafer is firmly fixed by the reinforcing plate 2, the scribe is performed. There are few occurrences of cracks and chips at the time, and it is possible to cleanly separate the chips, and it is possible to separate the chips in a small size.
[0066]
Furthermore, by setting the scribe direction to a first direction that coincides with the cleavage direction of the substrate 1 and a second direction that is orthogonal to the first direction, chip cracks and chips can be further reduced.
[0067]
As described above, in the chip having the dividing direction in the first direction that coincides with the cleavage direction of the substrate 1, the unevenness (roughness) of the dividing surface formed by the scribe is divided by the scribe in the first direction. There is a feature that the divided surface formed by scribing in the second direction is rougher than the surface, and of the four chip divided surfaces in the quadrilateral chip, two divided surfaces 1a and 2a facing each other. A light emitting element having a higher light extraction efficiency than the other two divided surfaces 3a and 4a can be manufactured, and such an element can have anisotropy in emission intensity.
[0068]
From the above, by using the method of attaching the wafer to the reinforcing plate 2 with an adhesive or a double-sided pressure-sensitive adhesive sheet and scribing the wafer, chip breakage and chipping can be reduced, and the chip can be obtained with a high yield and a small size. Can be formed.
[0069]
【Example】
Hereinafter, a nitride semiconductor chip and a manufacturing method thereof according to the present invention will be described with reference to the drawing (FIG. 1).
[0070]
Example 1
A specific example of a nitride semiconductor chip separation method using a substrate, which has been difficult to separate by conventional methods, will be described.
[0071]
The substrate 1 is a GaN substrate that is a hexagonal nitride semiconductor. First, a GaN substrate having a thickness of 300 μm and a 2 inch φ (0001) surface as a main surface was prepared, and organic cleaning was performed.
[0072]
Next, the GaN substrate is inserted into a MOCVD (metal organic chemical vapor deposition) apparatus, and a Si-doped n-type GaN underlayer, a non-doped n-type AlGaN cladding layer, a non-doped InGaN light emitting layer, a non-doped layer are formed on the main surface of the GaN substrate. A GaN intermediate layer, an Mg doped p-type AlGaN cladding layer, and an Mg doped p-type AlGaN contact layer were sequentially laminated.
[0073]
On the surface of the nitride semiconductor multilayer film formed in this way, SiO is formed by CVD. ₂ After depositing an insulating film made of and forming a mask made of an insulating film exposing a part of the surface by photolithography and RIE, a nitride semiconductor laminated film is formed from the exposed surface by RIE using a chlorine-based gas. Etching was performed in the depth direction to expose the Si-doped n-type GaN underlayer.
[0074]
Thereafter, the mask is removed by wet etching, and a p-electrode is exposed by stacking platinum and gold on the surface of the Mg-doped p-type AlGaN contact layer by photolithography and vapor deposition, below the Si-doped n-type GaN. An n-electrode was formed by laminating titanium and gold on the surface of the base layer to form a light emitting diode element structure.
[0075]
In this way, a nitride semiconductor device structure was formed on the main surface of the substrate 1.
[0076]
Next, in order to attach the wafer on the reinforcing plate 2 made of a Si substrate having a thickness of 1 mm and a 2.5 inch diameter, the reinforcing plate 2 is placed on a hot plate and heated to 120 ° C. Then, the stick-shaped semiconductor wax is uniformly stretched while melting to a size of 2 inches φ, and the wafer is placed on the stretched wax so that the side on which the nitride semiconductor element structure is formed becomes an adhesive surface. The adhesive surface was vented while pressing the top (GaN substrate side). When the wafer attached to the reinforcing plate 2 is cooled, it is lightly pressed with a flat surface jig or the like to eliminate wasteful wax on the bonding surface and wipe off the wax protruding from the wafer with an organic solvent. It was.
[0077]
The wafer reinforced by sticking to the reinforcing plate 2 in this way was scribed with a chip size of 300 μm square.
[0078]
First, the reinforcing plate 2 side was attached to the scriber stage by vacuum suction so that the scribe direction and the orientation flat direction of the wafer (the <11-20> direction of the GaN substrate) were parallel.
[0079]
Then, scribing was performed a total of four times at 10 positions of A- (4) (parallel to the orientation flat direction), and it was confirmed that the wafer was divided with an optical microscope attached to the scriber.
[0080]
A thin scribe line was confirmed in the first and second scribes, and a partial crack along the scribe line was confirmed in the third scribe. At the time of the fourth scribing, continuous cracks were observed along the scribe line from end to end of the wafer. That is, at this point, the wafer was completely divided by the scribe line.
[0081]
Then, after scribing the entire surface of the wafer four times at intervals of 300 μm, scribing was performed four times at intervals of 300 μm in the same direction (in this case, the cleavage direction of the GaN substrate) perpendicular to the scribe line. .
[0082]
After scribing the entire wafer surface into chips, air was lightly blown onto the scribed surface with an air gun, and fine chips generated by scribing were blown away.
[0083]
Next, with the chip attached to the reinforcing plate 2, the chip was placed in a beaker containing acetone and washed for 5 minutes. When the ultrasonic wave was irradiated, the chip could be peeled from the reinforcing plate 2 in a short time.
[0084]
By doing so, all the chips settled on the bottom of the beaker, and the chips could be completely peeled off from the auxiliary reinforcing plate 2 and the wax adhered to the chips could be removed. Then, after replacing with acetone three times, only the chips were collected with filter paper, and the whole filter paper was dried in a drying furnace.
[0085]
When the chip thus obtained was confirmed with an optical microscope, the chip was found to have a beautiful chip cross section with few cracks and chips. The yield for a 2-inch φ wafer was 90% or more.
[0086]
(Example 2)
A wafer having a nitride semiconductor element structure formed on the main surface of a substrate 1 made of GaN having a thickness of 300 μm and 2 inches of φ was prepared in the same manner as in Example 1.
[0087]
Next, a ceramic polishing jig having a diameter of 100 mmφ is heated to 120 ° C. with a hot plate, and the entire surface of the wafer is bonded to the side of the wafer where the nitride semiconductor element structure is formed using a semiconductor wax. And bonded to a polishing jig. And the whole wafer surface is 2kg / cm ² In addition to removing unnecessary wax, the polishing jig and the wafer were cooled.
[0088]
After cooling, the polishing jig was mounted on a grinder and ground from the GaN substrate side to a wafer thickness of 160 μm, and then mirror-polished with a lapping apparatus to a thickness of 150 μm by diamond graining.
[0089]
Next, the polishing jig was heated to 120 ° C. with a hot plate to soften the wax, and then the wafer was removed and the adhered wax was removed by washing with acetone.
[0090]
In this way, a 150 μm thick wafer having a nitride semiconductor element structure formed on the main surface of the substrate 1 was prepared.
[0091]
Thereafter, the wafer was attached to the reinforcing plate 2 in the same manner as in Example 1.
[0092]
The wafer reinforced by sticking to the reinforcing plate 2 in this way was scribed with a chip size of 300 μm square.
[0093]
First, the reinforcing plate 2 side was attached to the scriber stage by vacuum suction so that the scribe direction and the orientation flat direction of the wafer (the <11-20> direction of the GaN substrate) were parallel.
[0094]
Then, scribing was performed a total of two times at 10 positions of A- (4) (parallel to the orientation flat direction), and it was confirmed that the wafer was divided with an optical microscope attached to the scriber.
[0095]
In the first scribe, partial cracks along the scribe line were confirmed. In the second scribe, a continuous crack was observed from end to end of the wafer along the scribe line. That is, at this point, the wafer was completely divided by the scribe line. It was confirmed that by thinning the wafer, the wafer was divided with a smaller number of scribes than in Example 1.
[0096]
Then, after scribing the entire surface of the wafer twice at intervals of 300 μm, scribing was also performed twice at intervals of 300 μm in the direction perpendicular to the scribe line (in this case, the cleavage direction of the GaN substrate). .
[0097]
Thereafter, the chip was peeled off from the reinforcing plate 2 in the same manner as in Example 1.
[0098]
When the chip thus obtained was confirmed with an optical microscope, the chip was found to have a beautiful chip cross section with few cracks and chips. The yield for a 2-inch φ wafer was 98% or more.
[0099]
(Example 3)
A nitride semiconductor chip was manufactured in the same manner as in Example 2 except that the chip size was changed to 250 μm square.
[0100]
When the obtained chip was confirmed with an optical microscope, the chip was found to have a beautiful chip section with few cracks and chips. The yield for a 2-inch diameter wafer was 95% or more.
[0101]
Example 4
A nitride semiconductor chip was produced in the same manner as in Example 2 except that a double-sided PSA sheet was used when the wafer was bonded to the reinforcing plate 2.
[0102]
First, a wafer having a thickness of 150 μm having a nitride semiconductor element structure formed on the main surface of the substrate 1 was prepared in the same manner as in Example 2.
[0103]
Next, a double-sided pressure-sensitive adhesive sheet shaped to about 2.2 inches φ was prepared. As the double-sided pressure-sensitive adhesive sheet, a sheet in which a pressure-sensitive adhesive material having a characteristic that the adhesiveness disappears by heating was applied only to the inner side of both sides was used.
[0104]
The wafer was affixed as follows. After sticking one side of the double-sided pressure-sensitive adhesive sheet on the other side of the double-sided pressure-sensitive adhesive sheet on the reinforcing plate 2 made of a Si substrate having a thickness of 1 mm and a 2.5 inch diameter, a wafer prepared on the other side of the double-sided pressure-sensitive adhesive sheet Pasted.
[0105]
At this time, an adhesive surface having a characteristic that the adhesiveness disappears by heating is provided on the side to which the wafer is attached. In order to secure the adhesive force, it was lightly pressed with a jig with a flat surface.
[0106]
The wafer reinforced by sticking to the reinforcing plate 2 in this way was scribed with a chip size of 300 μm square.
[0107]
First, the reinforcing plate 2 side was attached to the scriber stage by vacuum suction so that the scribe direction and the orientation flat direction of the wafer (the <11-20> direction of the GaN substrate) were parallel.
[0108]
Then, scribing was performed a total of three times at 10 positions of A- (4) (parallel to the orientation flat direction), and it was confirmed that the wafer was divided with an optical microscope attached to the scriber.
[0109]
A thin scribe line was confirmed in the first scribe, and a partial crack along the scribe line was confirmed in the second scribe. At the time of the third scribing, continuous cracks from the end of the wafer along the scribe line could be confirmed. That is, at this point, the wafer was completely divided by the scribe line.
[0110]
After that, after scribing the entire surface of the wafer three times at intervals of 300 μm, scribing was also performed three times at intervals of 300 μm in the direction perpendicular to the scribe line (in this case, the cleavage direction of the GaN substrate). .
[0111]
After scribing the entire wafer surface into chips, air was lightly blown onto the scribed surface with an air gun, and fine chips generated by scribing were blown away.
[0112]
Next, the reinforcing plate 2 was placed on a hot plate maintained at a surface temperature of about 110 ° C. for 20 seconds with the divided chips adhered, and then picked up and cooled.
[0113]
After cooling, in a state where the chips are arranged on the reinforcing plate 2 while being scribed, the surface of the reinforcing plate 2 on which the chips are placed is lightly covered with a single-sided adhesive sheet having weak adhesiveness and stretchability. I pressed it down. By carrying out like this, the chip | tip was able to be transferred to the single-sided adhesive sheet.
[0114]
The chips could be easily picked up one by one by expanding the single-sided adhesive sheet.
[0115]
When the chip thus obtained was confirmed with an optical microscope, the chip was found to have a beautiful chip cross section with few cracks and chips. The yield for a 2-inch diameter wafer was 95% or more.
[0116]
(Example 5)
A nitride semiconductor chip was produced in the same manner as in Example 4 except that the chip size was changed to 250 μm square.
[0117]
When the obtained chip was confirmed with an optical microscope, the chip was found to have a beautiful chip section with few cracks and chips. The yield for a 2-inch φ wafer was 90% or more.
[0118]
(Example 6)
A wafer having a nitride semiconductor element structure formed on the main surface of a substrate 1 made of GaN having a thickness of 300 μm and 2 inches of φ was prepared in the same manner as in Example 1.
[0119]
Next, a ceramic polishing jig having a thickness of 5 mm, a diameter of 100 mmφ, and both surfaces having high precision flatness (in-plane accuracy within ± 5 μm) is heated to 120 ° C. with a hot plate, and used for semiconductors. Wax was used to bond the entire surface of the wafer to the polishing jig, using the side of the wafer where the nitride semiconductor element structure was formed as the bonding surface. And the whole surface of the substrate is 2kg / cm ² In addition to removing unnecessary wax, the polishing jig and the wafer were cooled.
[0120]
Then, the polishing jig was mounted on a grinding machine, the GaN substrate was ground to a thickness of 160 μm, and then mirror-polished to a thickness of 150 μm by diamond lapping using a lapping apparatus.
[0121]
The wafer thus obtained was fixed to the scriber stage by vacuum suction while being attached to the polishing jig.
[0122]
Then, the GaN substrate side of the wafer was scribed by the same method as in Example 1 to divide the chip into chips each having a chip size of 300 μm. Similar to the case of Example 2, the number of scribes necessary for the division was twice per line.
[0123]
Finally, the polishing jig was placed in a beaker containing acetone with the chips attached, and cleaning was performed for 5 minutes. In addition, the chip | tip was able to be peeled from the grinding | polishing jig | tool for a short time by irradiating an ultrasonic wave.
[0124]
Then, the chip peeled off from the polishing jig was dried by the same method as in Example 1.
[0125]
When the chip thus obtained was confirmed with an optical microscope, the chip was found to have a beautiful chip cross section with few cracks and chips. The yield for a 2-inch φ wafer was 98% or more.
[0126]
Further, by using a polishing jig instead of the reinforcing plate 2, the labor of attaching the wafer to the reinforcing plate 2 can be saved, and a series of chip separation steps of the wafer can be shortened.
[0127]
(Example 7)
A nitride semiconductor chip was produced in the same manner as in Example 6 except that the chip size was changed to 250 μm square.
[0128]
When the obtained chip was confirmed with an optical microscope, the chip was found to have a beautiful chip section with few cracks and chips. The yield for a 2-inch diameter wafer was 95% or more.
[0129]
The chip obtained by the above embodiment has the unevenness (roughness) of two facing divided surfaces that coincide with the cleavage direction of the substrate 1 among the four divided surfaces of the chip, and the unevenness (roughness) of other divided surfaces ( It is possible to make the light extraction efficiency from the divided surface of the chip anisotropic.
[0130]
Here, the light emitting diode chip separation method has been described as an example of the nitride semiconductor element, but it can also be applied to chip separation of a semiconductor laser, a light receiving element, an electronic device, or the like.
[0131]
【The invention's effect】
As described above, according to the present invention, when the wafer on which the nitride semiconductor device structure is formed is separated into chips, it is possible to suppress chip cracking and chipping, thereby improving chip yield. In addition, the effect that the chip size can be reduced can be obtained. Moreover, the effect that a manufacturing process can be simplified is also acquired. As a result, the manufacturing cost of the nitride semiconductor device can be reduced.
[Brief description of the drawings]
FIG. 1 is a diagram showing a method for manufacturing a nitride semiconductor chip according to an embodiment of the present invention.
[Explanation of symbols]
1 Substrate
1a, 2a, 3a, 4a Dividing plane
2 Reinforcing plate
3 Adhesive
4 n layers
5 Active layer
6 p layer
7 p electrode
8 n electrode
9, 10, 11, 12, 13, 14 Scribe line formation position

Claims (9)

A method for manufacturing a nitride semiconductor chip, wherein a wafer having a nitride semiconductor device structure formed on a main surface of a substrate is separated into chips, the wafer being bonded to both sides of the reinforcing plate on the main surface. A step of pasting through a sheet having at least one property of adherence and adhesion and capable of expanding; a step of dividing the wafer into chips by scribing; and a step of peeling the sheet from the reinforcing plate; fabrication of a nitride semiconductor chip, wherein the step of peeling the chip from the sheet, in that it consists of. 2. The method of manufacturing a nitride semiconductor chip according to claim 1, wherein the wafer is previously adjusted to a thickness of 50 to 200 [mu] m . 3. The method of manufacturing a nitride semiconductor chip according to claim 1, wherein an angle between any two cleavage planes orthogonal to the main surface is different from a right angle on the main surface of the substrate. . The method for manufacturing a nitride semiconductor chip according to claim 1, wherein the substrate is made of sapphire . The method for manufacturing a nitride semiconductor chip according to claim 1, wherein the substrate is made of hexagonal SiC . The method for manufacturing a nitride semiconductor chip according to claim 1 , wherein the substrate is made of a hexagonal nitride semiconductor . The method for manufacturing a nitride semiconductor chip according to claim 6 , wherein the substrate is made of hexagonal GaN . Wherein the substrate is made of a cubic semiconductor (111) nitride semiconductor chip manufacturing method according to claim 1 to 3, characterized in that a plane main surface. Wherein the first direction scribe direction matches the cleavage direction of the substrate, the nitride semiconductor chip according to claim 1-8, characterized in that a second direction perpendicular to said first direction Production method.

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