Semiconductor device manufacturing method

Abstract

A semiconductor layer (2) is formed on a semiconductor substrate (1). A resonator (3) is formed in the semiconductor layer (2). The semiconductor layer (2) is etched to form a chip separation groove (22) along the resonance direction of the resonator (3), and a wedge-shaped inverted mesa ridge structure (23) is formed in the center of the chip separation groove (22). A load is applied from above to the inverted mesa ridge structure (23) to separate the semiconductor substrate (1) into chips.

Description

[Technical Field]

[0001] The present disclosure relates to a semiconductor device and a manufacturing method thereof. [Background technology]

[0002] A scribing method, which involves forming scribe lines and applying a load, is known as a technique for separating a semiconductor substrate into individual chips (see, for example, Patent Document 1). In the scribing method, a separation area called a chip separation groove is first formed between the chips, and a scribe line is introduced into the separation area on the semiconductor substrate using a diamond tool. This forms microcracks along the scribe line. Next, stress is applied to open the microcracks, causing them to propagate and separating the substrate.

[0003] This scribing method is particularly effective for brittle substrate materials because it can suppress cracking compared to separation using a rotary blade or laser processing and increases the strength of the separated chips. These techniques are used for separation surfaces that do not require smoothness, such as the chip side surfaces where the laser light does not exit. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 11-274653 Summary of the Invention [Problem to be solved by the invention]

[0005] However, to achieve accurate separation, the load value and push-in amount during the scribe formation process must be optimized for each product, making process management difficult. Additionally, the scribe blade wears out, which increases costs.

[0006] The present disclosure has been made to solve the above-mentioned problems, and its object is to provide a semiconductor device and a manufacturing method thereof that can separate a semiconductor substrate into chips without scribing. [Means for solving the problem]

[0007] The method for manufacturing a semiconductor device according to the present disclosure is characterized by comprising the steps of: forming a semiconductor layer on a semiconductor substrate; forming a resonator in the semiconductor layer; etching the semiconductor layer to form a chip separation groove along the resonance direction of the resonator and forming a wedge-shaped inverted mesa ridge structure in the center of the chip separation groove; and separating the semiconductor substrate into chips by applying a load to the inverted mesa ridge structure from above. [Effects of the Invention]

[0008] In the present disclosure, a wedge-shaped inverted mesa ridge structure is formed in the center of the chip separation groove, and the semiconductor substrate is separated by applying a load from above to the inverted mesa ridge structure, which allows the semiconductor substrate to be separated into chips without scribing. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view showing a semiconductor device according to a first embodiment. [Figure 2] 1 is a cross-sectional view showing an LD portion of a semiconductor device according to a first embodiment. [Figure 3] 2A to 2C are cross-sectional views showing a manufacturing process of the semiconductor device according to the first embodiment. [Figure 4] 2A to 2C are cross-sectional views showing a manufacturing process of the semiconductor device according to the first embodiment. [Figure 5] 2A to 2C are cross-sectional views showing a manufacturing process of the semiconductor device according to the first embodiment. [Figure 6] 10A to 10C are cross-sectional views showing a manufacturing process of a semiconductor device according to a second embodiment. [Figure 7] 10A to 10C are cross-sectional views showing a manufacturing process of a semiconductor device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] A semiconductor device and a manufacturing method thereof according to an embodiment will be described with reference to the drawings. The same or corresponding components are designated by the same reference numerals, and repeated description may be omitted.

[0011] Embodiment 1 FIG. 1 is a perspective view showing a semiconductor device according to a first embodiment. This semiconductor device has a low mesa structure. A semiconductor substrate 1 is a compound semiconductor substrate such as n-InP or p-InP. A semiconductor layer 2 is formed on the semiconductor substrate 1. The semiconductor layer 2 has a ridge-type resonator 3.

[0012] The resonator 3 has, along the resonance direction, an LD section 4 which is a laser diode, an EA section 5 which is an electroabsorption modulator, and an isolation section 6 therebetween.

[0013] In the LD section 4, an active layer 7 and a cladding layer 8 are stacked in this order as the semiconductor layer 2 on a semiconductor substrate 1. In the EA section 5, a light absorption layer 9 and a cladding layer 8 are stacked in this order as the semiconductor layer 2 on a semiconductor substrate 1. A ridge structure is formed in the cladding layer 8. An insulating film 10 made of SiO2 is formed on the side surfaces and top surface of the cladding layer 8 and the ridge structure.

[0014] In the LD section 4, a front metal film 11 and a front plating film 12 are formed in this order on an insulating film 10, and are connected to the cladding layer 8 through an opening in the insulating film 10. In the EA section 5, a front metal film 13 and a front plating film 14 are formed in this order on an insulating film 10, and are connected to the cladding layer 8 through an opening in the insulating film 10. A back metal film 15 and a back plating film 16 are formed in this order on the back surface of the semiconductor substrate 1.

[0015] The width of the semiconductor substrate 1 is approximately 200 to 300 μm. The cavity length is approximately 600 to 800 μm. The modulator length is 100 to 200 μm. The isolation length is 50 to 100 μm. The LD length is 300 to 400 μm. The chip thickness is approximately 100 μm. The ridge height is approximately 3 to 5 μm. The thickness of the insulating film 10 is 500 to 1000 nm. The thickness of the front metal films 11 and 13 is 200 to 300 nm. The thickness of the front plating films 12 and 14 is 3 to 5 μm. The thickness of the back metal film 15 is 300 to 400 nm. The thickness of the back plating film 16 is 3 to 5 μm.

[0016] At the emission end face and rear end face of the resonator 3, the side faces of the semiconductor substrate 1 and the semiconductor layer 2 are flat cleavage planes. On the other hand, at the chip separation portion 17 along the resonance direction of the resonator 3, the side face of the semiconductor layer 2 has an inverse tapered shape, and the side face of the semiconductor substrate 1 is a vertical plane perpendicular to the main surface of the semiconductor substrate 1.

[0017] 2 is a cross-sectional view showing the LD portion of the semiconductor device according to embodiment 1. The semiconductor substrate 1 is made of n-InP. On the semiconductor substrate 1, an active layer 7, a p-InP layer 18, a p-InGaAs diffraction grating 19, a p-InP cladding layer 20, and a p-InGaAs contact layer 21 are stacked in this order as a semiconductor layer 2.

[0018] The semiconductor layer 2 on the active layer 7 has a ridge structure. The ridge width is 2 to 3 μm. The active layer 7 is made of an alternating stack of barrier layers and well layers made of InGaAsP. The surface metal film 11 is made of Cr / Au.

[0019] 3 to 5 are cross-sectional views showing the manufacturing process of the semiconductor device according to the embodiment 1. Fig. 4 is an enlarged cross-sectional view of the chip separation portion of Fig. 3.

[0020] First, as shown in FIGS. 3 and 4, a semiconductor laminate structure is formed on a semiconductor substrate 1, and this semiconductor laminate structure is etched to form a ridge-type resonator 3. Both sides of the resonator 3 are buried with a burying layer 22. A contact layer 23 is formed on the resonator 3 and the burying layer 22. The resonator 3, the burying layer 22, and the contact layer 23 correspond to the semiconductor layer 2. The semiconductor layer 2 is etched to form a chip separation groove 24 along the resonance direction of the resonator 3, and a wedge-shaped inverted mesa ridge structure 25 is formed in the center of the chip separation groove 24. Specifically, an insulating film hard mask is formed on the semiconductor layer 2, and the semiconductor layer 2 is wet-etched to form the inverted mesa ridge structure 25. That is, the inverted mesa ridge structure 25 is formed by utilizing the surface orientation dependency of wet etching of semiconductors. The etchant for wet etching is, for example, HBr.

[0021] 5, a load is applied from above to the inverted mesa ridge structure 25 through the cleavage sheet 27 using a pressing tool 26, thereby separating the semiconductor substrate 1 into chips. This allows the semiconductor substrate 1 to be separated into chips without scribing.

[0022] It is desirable not to form a semiconductor, metal, or insulating film that is difficult to break, such as InGaAs, in the chip separation groove 24 to which a load is applied, so as to easily break the semiconductor substrate 1. However, if an insulating film, metal, or the like has been formed in another process so as to cover the inverted mesa ridge structure 25, it may be left as it is.

[0023] Embodiment 2 6 and 7 are cross-sectional views showing manufacturing processes for a semiconductor device according to the second embodiment. As shown in FIG. 6, metal films 28 and 29 are formed on the inverted mesa ridge structure 25. The metal film 29 is a plating film. This increases the height of the metal films 28 and 29 on the inverted mesa ridge structure 25. This reduces the difference in height between the metal films 28 and 29 and the front plating film 12 on the surrounding semiconductor layer 2, making it easier to apply a load to the inverted mesa ridge structure 25 during breaking. Note that the metal films 28 and 29 are formed in a separate process from the front plating film 12 on the surrounding semiconductor layer 2. The height of the metal film 29 may be higher than the surrounding front plating film 12.

[0024] 7, roller breaking is performed in which a roller 30 is rolled on the semiconductor layer 2 to apply a load from above to the metal films 28, 29 on the inverted mesa ridge structure 25, thereby separating the semiconductor substrate 1 into chips. Using roller breaking can reduce the cost of chip separation. The other structures, processes, and effects are the same as those of the first embodiment. [Explanation of symbols]

[0025] 1 semiconductor substrate, 2 semiconductor layer, 3 resonator, 17 chip separation section, 24 chip separation groove, 25 inverted mesa ridge structure, 28, 29 metal film, 30 roller

Claims

1. forming a semiconductor layer on a semiconductor substrate; forming a resonator in the semiconductor layer; a step of etching the semiconductor layer to form a chip separation groove along a resonance direction of the resonator, and forming a wedge-shaped inverted mesa ridge structure in a center of the chip separation groove; and applying a load from above to the inverted mesa ridge structure to separate the semiconductor substrate into chips.

2. 2. The method for manufacturing a semiconductor device according to claim 1, wherein the semiconductor layer is wet-etched to form the inverted mesa ridge structure.

3. forming a first metal film on the resonator; 3. The method for manufacturing a semiconductor device according to claim 1, further comprising the step of forming a second metal film on the inverted mesa ridge structure.

4. 4. The method for manufacturing a semiconductor device according to claim 3, wherein the semiconductor substrate is separated into chips by rolling a roller over the semiconductor layer to apply a load from above to the second metal film over the inverted mesa ridge structure.

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