CN100397735C

CN100397735C - Ridge waveguide type semiconductor laser and its manufacturing method

Info

Publication number: CN100397735C
Application number: CNB2005101009023A
Authority: CN
Inventors: 李络; 周耀辉
Original assignee: Shenzhen Neo Photonic Technology Co Ltd
Current assignee: Longmet Communication Technology Shenzhen Co ltd
Priority date: 2005-10-29
Filing date: 2005-10-29
Publication date: 2008-06-25
Anticipated expiration: 2025-10-29
Also published as: CN1956284A

Abstract

This invention provides a ridge waveguide semiconductor laser and its manufacturing method including wafers with ridge waveguide humps, two sides from the bottom to the top of the hump includes: a layer of SiO2 azotized film and a layer of polyimide film and the top surface of which is higher than that of the hump, the P-type electrode covers the top surface of the hump and the polyimide film to form ohm contact, the N-type electrode is formed at the bottom surface of the wafer, the two sides of the ridge waveguide are filled effectively by the polyimide film so as to increase the covering ability of steamed metal electrodes and improve ohm contact of P type-electrodes.

Description

The ridge waveguide type semiconductor laser manufacture method

Technical field

The present invention relates to a kind of ridge waveguide type semiconductor optical device, relate in particular to a kind of ridge waveguide type semiconductor laser manufacture method.

Background technology

The profile of traditional ridge waveguide type semiconductor laser as shown in Figure 9, comprise wafer 1 with ridge waveguide projection 8, the both side surface of ridge waveguide projection 8 is formed with silicon dioxide passivating film 2, and make the upper space that P type electrode 3 covers wafer 1 at last, N type electrode 3 ' the be formed on bottom of wafer 1.Its manufacture method adopts dry method RIE etching or chemical corrosion method to erode away ridge waveguide projection 8, then by PECVD growth layer of silicon dioxide passivating film 2, etches away the silicon dioxide passivating film 2 of the upper surface portion of ridge waveguide projection 8 again.This process is simple, but the height of the ridge waveguide projection 8 that shortcoming is an etching comes out is usually about 2 μ m, like this, the top layer and the difference in height between the etching stop layer of ridge waveguide projection 8 are obvious, and the usually precipitous or inside contraction in the two sides of the ridge waveguide projection 8 that erodes away forms inverted trapezoidal structure, P type electrode 3 is difficult to cover the both sides of ridge waveguide projection 8 like this, in semiconductor laser chip technological operation and encapsulation process, damage ridge waveguide projection 8 easily and cause chip failure, poor reliability, series resistance is big, also blows electrode easily under the situation of big electric current.

Summary of the invention

Goal of the invention: for overcoming above shortcoming, when the invention provides a kind of the encapsulation ridge waveguide projection be difficult for impaired, ohmic contact good, technology is simple and the ridge waveguide type semiconductor laser manufacture method of good reliability.

For realizing above goal of the invention, the invention provides a kind of manufacture method of ridge waveguide type semiconductor laser, its operating sequence is as follows:

A, on semiconductor epitaxial wafer growth layer of silicon dioxide film, shelter down at it, make the ridge waveguide projection by lithography, its width is controlled at about 2 μ m, forms ridge waveguide wafer after washing photoresist;

B, ridge waveguide wafer is removed the silicon dioxide film of sheltering usefulness in hydrofluoric acid, after cleaning up, cover the upper surface of ridge waveguide wafer by PECVD growth layer of silicon dioxide passivating film;

C, at surface applied one deck polyimide film of the silicon dioxide passivating film of ridge waveguide wafer, make its both sides that are filled in the ridge waveguide projection, and make the upper surface of whole polyimide film be higher than the upper surface of ridge waveguide projection;

D, under protection of nitrogen gas, adopt the ladder-elevating temperature method that the polyimide film of ridge waveguide wafer upper surface is carried out imidization and handles after, be coated with the thick positive photoresist of last layer again, according to the design of mask, exposure imaging;

E, the ridge waveguide wafer that will scribble positive photoresist are put in the plasma degumming machine, carry out plasma etching, and bombardment falls the polyimide film of ridge waveguide projection upper surface, after etching is finished, removes the residue positive photoresist of whole polyimide film upper surface fully in acetone;

F, the ridge waveguide wafer after positive photoresist cleaned up erode the silicon dioxide passivating film of ridge waveguide projection upper surface in hydrofluoric acid;

G, evaporation P type electrode and N type electrode, alloy.

Invention effect: because effective filling has been carried out by polyimide film in the both sides of the ridge waveguide projection of said structure, improved the covering power of evaporated metal electrode, improved the ohmic contact of metal P type electrode, thereby reduced series resistance, and because the film formed smooth flanks of polyimides has prevented sharp-pointed precipitous ridge waveguide edge because the overheated open circuit that causes, upper surface owing to the ridge waveguide projection is lower than the polyimide film upper surface of both sides simultaneously, thereby avoids in chip technology operation and Chip Packaging process because the impaired chip failure that causes of ridge waveguide projection.

Description of drawings

What Fig. 1 represented that ridge waveguide type semiconductor laser method of the present invention makes covers the profile of ridge waveguide wafer down at the silicon dioxide film hole;

Fig. 2 represents to remove the profile of the ridge waveguide wafer after silicon dioxide film hole shown in Figure 1 covers;

Fig. 3 is illustrated in the profile that forms the layer of silicon dioxide passivating film on the ridge waveguide wafer shown in Figure 2;

Fig. 4 is illustrated in the profile that silicon dioxide passivating film surface shown in Figure 3 forms one deck polyimide film;

Fig. 5 is illustrated in the profile that polyimide film surface shown in Figure 4 forms one deck positive photoresist;

Fig. 6 represents to remove the profile of the polyimides of positive photoresist shown in Figure 5 and ridge waveguide protrusion surface;

Fig. 7 represents to remove the profile behind the silicon dioxide passivating film of ridge waveguide protrusion surface shown in Figure 6;

Fig. 8 represents ridge waveguide type semiconductor laser of the present invention;

Fig. 9 represents the profile of conventional ridge formula semiconductor laser.

Embodiment

The ridge waveguide type semiconductor laser made of the inventive method as shown in Figure 8, comprise ridge waveguide wafer 1 with ridge waveguide projection 8, the both sides that are positioned at ridge waveguide projection 8 comprise from bottom to top: layer of silicon dioxide passivating film 2 and one deck polyimide film 4, and the upper surface of this polyimide film 4 is higher than the upper surface of ridge waveguide projection 8, P type electrode 6 cover the upper surface of described ridge waveguide projection 8 and be positioned at its both sides polyimide film 4 upper surface and form ohmic contact, N type electrode 6 ' is formed on the lower surface of ridge waveguide wafer 1.

The manufacture method of ridge waveguide type semiconductor laser of the present invention is operated in the following order:

A, on semiconductor epitaxial wafer growth layer of silicon dioxide film 9, shelter down at it, make ridge waveguide projection 8 by lithography, its width is controlled at about 2 μ m, washes the ridge waveguide wafer 1 that forms behind the photoresist as shown in Figure 1;

B, with ridge waveguide wafer shown in Figure 11 in hydrofluoric acid, remove shelter usefulness silicon dioxide film 9 as shown in Figure 2, after cleaning up, cover the upper surface of ridge waveguide wafer 1 by PECVD growth layer of silicon dioxide passivating film 2, form profile as shown in Figure 3;

C, at surface applied one deck polyimide film 4 of the silicon dioxide passivating film 2 of ridge waveguide wafer 1, make it be filled in the both sides of ridge waveguide projection 8, and the upper surface that makes whole polyimide film 4 is higher than the upper surface of ridge waveguide projection 8, profile as shown in Figure 4;

D, under protection of nitrogen gas, after adopting the ladder-elevating temperature method that the polyimide film 4 of ridge waveguide wafer 1 upper surface is carried out imidization and handles, be coated with the thick positive photoresist of last layer 5 again, according to the design of mask, by exposure imaging, form profile as shown in Figure 5;

E, the ridge waveguide wafer 1 that will scribble positive photoresist 5 are put in the plasma degumming machine, carry out plasma etching, and the polyimide film 4 of ridge waveguide projection 8 upper surfaces is fallen in bombardment, after etching is finished, in acetone, remove the residue positive photoresist 5 of whole polyimide film 4 upper surfaces fully, form profile as shown in Figure 6;

F, the ridge waveguide wafer 1 after positive photoresist 5 cleaned up erode the silicon dioxide passivating film 2 of ridge waveguide projection 8 upper surfaces in hydrofluoric acid, form profile as shown in Figure 7;

G, evaporation P type electrode 6 and N type electrode 6 ', alloy forms ridge waveguide type semiconductor laser of the present invention, as shown in Figure 8.

Claims

1. the manufacture method of a ridge waveguide type semiconductor laser is characterized in that, its operating sequence is as follows:

A, on semiconductor epitaxial wafer growth layer of silicon dioxide film (9), shelter down at it, make ridge waveguide projection (8) by lithography, its width is controlled at about 2 μ m, forms ridge waveguide wafer (1) after washing photoresist;

B, ridge waveguide wafer (1) is removed the silicon dioxide film (9) of sheltering usefulness in hydrofluoric acid, after cleaning up, cover the upper surface of ridge waveguide wafer (1) by PECVD growth layer of silicon dioxide passivating film (2);

C, at surface applied one deck polyimide film (4) of the silicon dioxide passivating film (2) of ridge waveguide wafer (1), make its both sides that are filled in ridge waveguide projection (8), and make the upper surface of whole polyimide film (4) be higher than the upper surface of ridge waveguide projection (8);

D, under protection of nitrogen gas, adopt the ladder-elevating temperature method that the polyimide film (4) of ridge waveguide wafer (1) upper surface is carried out imidization and handles after, be coated with the thick positive photoresist of last layer (5) again, according to the design of mask, exposure imaging;

E, the ridge waveguide wafer (1) that will scribble positive photoresist (5) are put in the plasma degumming machine, carry out plasma etching, and the polyimide film (4) of ridge waveguide projection (8) upper surface is fallen in bombardment, after etching is finished, in acetone, remove the residue positive photoresist (5) of whole polyimide film (4) upper surface fully;

F, the ridge waveguide wafer (1) after positive photoresist (5) cleaned up erode the silicon dioxide passivating film (2) of ridge waveguide projection (8) upper surface in hydrofluoric acid;

G, evaporation P type electrode (6) and N type electrode (6 ') carry out alloy to P type electrode (6) and the N type electrode (6 ') that is evaporated.