Method for inspecting semiconductor device and method for manufacturing semiconductor device

Abstract

The method for inspecting a semiconductor device according to the present disclosure includes a semiconductor device including a semiconductor substrate, an active layer provided on the semiconductor substrate, a contact layer provided on the active layer, a pair of block layers provided on both sides of the active layer on the semiconductor substrate, a main electrode provided on the contact layer, a back electrode provided on the side of the semiconductor substrate opposite the active layer, and an additional electrode provided on at least one of the pair of block layers, and after a first current is passed between the main electrode and the additional electrode, a second current is passed between the main electrode and the back electrode, and characteristics of the semiconductor device are measured between the first current and the second current and after the second current.

Description

[Technical field]

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

[0002] Patent Document 1 discloses a semiconductor laser having a configuration that allows direct measurement of electrical characteristics. This semiconductor laser has a first conductive cladding layer, an active layer, a second conductive cladding layer partly forming a ridge structure, and a current confinement layer stacked on a substrate. In addition, a plurality of electrodes electrically isolated from each other are formed on the current confinement layer so as to cross the ridge structure. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-192765 A Summary of the Invention [Problem to be solved by the invention]

[0004] Generally, in the manufacturing process of semiconductor lasers, a burn-in process is performed in which an electric current is passed through the device in order to select devices with problems in characteristic stabilization and reliability. In the burn-in process, devices that meet the reliability requirements of the market are selected based on the amount of characteristic variation before and after the burn-in.

[0005] In general, in order to obtain a sufficient selection effect by burn-in in a buried semiconductor laser, current injection only near the active layer is insufficient. For this reason, for example, a large current exceeding the current at which the optical output-current characteristic saturates is passed to simultaneously inject current into the active layer, block layer, and contact layer. In this case, the characteristic fluctuation before and after burn-in becomes too large, making it impossible to perform accurate and proper selection, and the selection by burn-in may result in excessive quality.

[0006] An object of the present disclosure is to provide a semiconductor device inspection method and a semiconductor device manufacturing method that are capable of appropriately evaluating characteristic variations due to burn-in. [Means for solving the problem]

[0007] A method for inspecting a semiconductor device according to the present disclosure includes a semiconductor substrate, an active layer provided on the semiconductor substrate, a contact layer provided on the active layer, a pair of block layers provided on both sides of the active layer on the semiconductor substrate, a main electrode provided on the contact layer, a back electrode provided on the side of the semiconductor substrate opposite the active layer, and an additional electrode provided on at least one of the pair of block layers, the method comprising: conducting a first current between the main electrode and the additional electrode, and then conducting a second current between the main electrode and the back electrode; and measuring characteristics of the semiconductor device between the first current and the second current and after the second current. The second energization current is smaller than the first energization current. . Effect of the Invention

[0008] In the semiconductor device inspection method according to the present disclosure, a first current is passed between the main electrode and the additional electrode, a second current is passed between the main electrode and the back electrode, and the characteristics of the semiconductor device are measured between the first current and the second current and after the second current, thereby making it possible to appropriately evaluate the characteristic fluctuation due to burn-in. [Brief description of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view of a semiconductor device according to a first embodiment. [Diagram 2] 1 is a plan view of a semiconductor device according to a first embodiment. [Diagram 3] 4 is a flowchart illustrating a method for inspecting a semiconductor device according to the first embodiment. [Figure 4] FIG. 11 is a cross-sectional view of a semiconductor device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] A semiconductor device inspection method and a semiconductor device manufacturing method according to each 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 cross-sectional view of a semiconductor device 100 according to a first embodiment. FIG 2 is a plan view of the semiconductor device 100 according to the first embodiment. The semiconductor device 100 is a semiconductor laser such as a Fabry-Perot laser. The semiconductor device 100 includes a semiconductor substrate made of, for example, n-InP. A cladding layer 12, an active layer 14, and a cladding layer 16 are laminated in this order on the semiconductor substrate 10. The cladding layer 12 is made of, for example, n-InP, and the cladding layer 16 is made of, for example, p-InP.

[0012] A pair of block layers are provided on both sides of the active layer 14 on the semiconductor substrate 10. Each block layer has a semi-insulating layer 20 provided on the semiconductor substrate 10, a block layer 22 provided on the semi-insulating layer 20, and a block layer 24 provided on the block layer 22. The block layer 22 is made of, for example, n-InP, and the block layer 24 is made of, for example, p-InP. In this way, the semiconductor device 100 has a buried structure in which both sides of the active layer 14 are buried.

[0013] A contact layer is provided on the cladding layer 16 and the pair of block layers. The contact layer has a contact layer 30 provided on the cladding layer 16 and a contact layer 32 provided on the contact layer 30. The contact layer 30 is made of, for example, p-InP, and the contact layer 32 is made of, for example, p-InGaAs.

[0014] A main electrode 40 is provided on the contact layer 32. The main electrode 40 is an electrode for supplying operating power to the laser. The main electrode 40 has an electrode 41 provided on the contact layer 32 and a plating 42 provided on the electrode 41. The electrode 41 is, for example, an electrode made of Ti, Pt, or Au, or a Cr electrode. The plating 42 is, for example, an Au plating.

[0015] Additional electrodes 45a, 45b are provided on the pair of block layers 22, respectively. As described below, the additional electrodes 45a, 45b are electrodes for passing electricity through the block layers. Each of the additional electrodes 45a, 45b has an electrode 46 provided on the block layer 22 and a plating 47 provided on the electrode 46. The electrode 46 is, for example, an electrode made of Ti, Pt, Au, or a Cr electrode. The plating 47 is, for example, an Au plating. The laminated structures of the additional electrodes 45a, 45b and the main electrode 40 may be the same or different.

[0016] A back electrode 50 is provided on the side of the semiconductor substrate 10 opposite to the active layer 14. The back electrode 50 has an electrode 51 provided under the semiconductor substrate 10 and a plating 52 provided under the electrode 51. The electrode 51 is an electrode made of, for example, Ge, Ni, Ti, Pt, or Au. The plating 52 is, for example, an Au plating.

[0017] An upper surface of the contact layer 32, side surfaces of the contact layers 30, 32 and the block layer 24, an upper surface of the block layer 22, and side surfaces of the block layer 22 and the semi-insulating layer 20 are covered with an insulating film 60. An opening is formed in the insulating film 60, for example, directly above the active layer 14. The main electrode 40 is provided in this opening. In addition, an opening is formed in the insulating film 60 above the pair of block layers. Additional electrodes 45a, 45b are provided in this opening.

[0018] 3 is a flowchart for explaining a method for inspecting the semiconductor device 100 according to the first embodiment. First, the characteristics of the semiconductor device 100 are measured (step 1). These characteristics are particularly those of the active layer 14. The characteristics are, for example, a threshold Ith at an arbitrary temperature such as 25° C. to 80° C., or a driving current Iop at a predetermined optical output such as 5 mW.

[0019] Next, a first current is passed between the main electrode 40 and the additional electrodes 45a and 45b (step 2). This allows current to be passed between the block layer and the contact layer. Current is also passed through the regrowth interface 25 that exists between the block layers 22 and 24, etc. In the first current, current is passed between the main electrode 40 and the additional electrode 45a and current is passed between the main electrode 40 and the additional electrode 45b essentially at the same time. Only one of the currents between the main electrode 40 and the additional electrode 45a and currents between the main electrode 40 and the additional electrode 45b may be passed, or they may be passed in sequence.

[0020] Next, the characteristics of the semiconductor device 100 are measured between the first energization in step 2 and the second energization described below (step 3). The characteristics measured in step 3 are, for example, the same items as the characteristics measured in step 1.

[0021] Next, after the first current flow and the measurement in step 3, a second current flow is performed between the main electrode 40 and the back electrode 50 (step 4). This allows current injection into the active layer 14 in the same manner as in normal device operation. The current during the second current flow may be larger than the current during normal device operation. The current flowing in the second current flow is smaller than the current flowing in the first current flow. The current flowing in the first current flow is, for example, 200 mA to 400 mA, and the current flowing in the second current flow is, for example, 50 mA to 200 mA.

[0022] Next, the characteristics of the semiconductor device 100 are measured again after the second current flow (step 5). The characteristics measured in step 5 are, for example, the same items as the characteristics measured in step 3. This makes it possible to measure characteristic fluctuations from the measurement results of steps 3 and 5.

[0023] Next, the effect of this embodiment will be described. In order to obtain a sufficient selection effect in a semiconductor laser, current injection only in the vicinity of the active layer is generally insufficient. For this reason, when selection is performed only by passing current between the main electrode 40 and the back electrode 50, a large current is passed through to simultaneously inject current into the active layer, the block layer, and the contact layer. In this case, there is a risk of excessive current injection into the active layer.

[0024] In contrast, in the present embodiment, a current can be injected into the block layer and the contact layer by the first current flow between the main electrode 40 and the additional electrodes 45a and 45b. Therefore, the current of the second current flow to the active layer 14 can be made smaller than in the past. Therefore, the characteristic fluctuation due to burn-in can be appropriately evaluated. In other words, excessive quality can be prevented, and the semiconductor device 100 having reliability sufficient for market supply can be appropriately selected.

[0025] In a modification of this embodiment, the additional electrode may be provided on at least one of the pair of blocking layers. The semiconductor device 100 may be a distributed feedback (DFB) laser, a DFB laser with a modulator, an electro-absorption modulator integrated laser diode (EML), or the like. In addition to the laser, the semiconductor device 100 may also have other optical components, such as a modulator and a semiconductor optical amplifier (SOA), monolithically integrated therein.

[0026] Moreover, the method for inspecting the semiconductor device 100 according to the present embodiment may be applied to the manufacturing process of the semiconductor device 100, thereby forming a manufacturing method of the semiconductor device 100.

[0027] The above-mentioned modifications can be appropriately applied to the semiconductor device inspection method and semiconductor device manufacturing method according to the following embodiments. Note that the semiconductor device inspection method and semiconductor device manufacturing method according to the following embodiments have many points in common with the first embodiment, so the differences from the first embodiment will be mainly described.

[0028] Embodiment 2 4 is a cross-sectional view of a semiconductor device 200 according to embodiment 2. The semiconductor device 200 has a different block layer structure from the semiconductor device 100 of embodiment 1. The other structures and inspection methods are similar to those of embodiment 1.

[0029] The semiconductor device 200 is, for example, an FP laser. The pair of block layers has a p / n / p structure. That is, each block layer has a block layer 220 which is a first p-type layer on the semiconductor substrate 10, a block layer 222 which is an n-type layer on the block layer 220, and a block layer 24 which is a second p-type layer on the block layer 222. The block layer 220 is formed of, for example, p-InP, the block layer 222 is formed of, for example, n-InP, and the block layer 24 is formed of, for example, p-InP. The block layer 220 covers the upper surface of the semiconductor substrate 10, the side surfaces of the cladding layers 12 and 16, and the side surface of the active layer 14.

[0030] The inspection method described in the first embodiment can be applied to such a semiconductor device 200. This makes it possible to appropriately evaluate the characteristic fluctuation due to burn-in, similarly to the first embodiment.

[0031] The technical features described in each embodiment may be used in appropriate combination. [Explanation of symbols]

[0032] 10 semiconductor substrate, 12 cladding layer, 14 active layer, 16 cladding layer, 20 semi-insulating layer, 22 blocking layer, 24 blocking layer, 25 regrowth interface, 30 contact layer, 32 contact layer, 40 main electrode, 41 electrode, 42 plating, 45a additional electrode, 45b additional electrode, 46 electrode, 47 plating, 50 back electrode, 51 electrode, 52 plating, 60 insulating film, 100 semiconductor device, 200 semiconductor device, 220 blocking layer, 222 blocking layer

Claims

1. A semiconductor substrate; an active layer provided on the semiconductor substrate; a contact layer provided on the active layer; a pair of block layers provided on both sides of the active layer on the semiconductor substrate; a main electrode provided on the contact layer; a back electrode provided on a side of the semiconductor substrate opposite to the active layer; an additional electrode provided on at least one of the pair of blocking layers; In a semiconductor device comprising: a first current is passed between the main electrode and the additional electrode, and then a second current is passed between the main electrode and the back electrode; measuring characteristics of the semiconductor device between the first current flow and the second current flow and after the second current flow; a second current supplying a current smaller than a first current supplying a current to the semiconductor device;

2. 2. The method for testing a semiconductor device according to claim 1, wherein the blocking layer comprises a semi-insulating layer.

3. 2. The method for inspecting a semiconductor device according to claim 1, wherein the blocking layer comprises a first p-type layer on the semiconductor substrate, an n-type layer on the first p-type layer, and a second p-type layer on the n-type layer.

4. A method for manufacturing a semiconductor device, comprising the method for inspecting a semiconductor device according to claim 1 .

Images