JPS58223382A - Semiconductor light emitting device - Google Patents

Abstract

PURPOSE:To prevent the blur or unsharpness of a light emitting part and enable to largely reduce the photo crosstalk between light emitting parts by providing a light untransmitting part composed of an insulation film and a light untransmitting film. CONSTITUTION:P type diffused regions 38 are formed on an n type semiconductor wafer 33. The first insulation film 34, light untransmitting film 35, and second insulation film 36 which covers it are formed successively on the surface of this wafer 33. These insulation films and the light untransmitting film compose the light untransmitting part 41. The light untransmitting part 41 is equipped with light emitting windows 37 on the diffused regions 38. The light untransmitting part 41 formed in this manner enables to prevent the leak to light toward the side or light scattered in the crystal from the non-light emitting regions. Thus, the blur or unsharpness of the light emitting part is prevented, and the light crosstalk can be largely reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a semiconductor light emitting device such as a light emitting diode, and is particularly used as a monolithic light emitting display or a light emitting diode array.

[Technical background of the invention and its problems]

2. Description of the Related Art Monolithic light emitting diodes having a plurality of light emitting parts have conventionally been used as display elements for wristwatches and calculators.

FIG. 1 shows a typical structure of such a monolithic light emitting diode having a plurality of light emitting parts. First, n-type GaAs1-xPx (0
(x(0,4) and n-type GaA[io, 6P+), 4
A diffusion mask 13 made of, for example, an At203 film is placed on the surface of a semiconductor wafer 12 on which an n-type layer 11 with a two-layer structure has been grown.
is deposited and Zn is diffused through the opening 14.14 to form a p-type diffusion region 15.15 that makes a pn junction with the n-type layer 11. Then, the opening 14 of the diffusion mask 13.
A p-type ohmic electrode 17.17 connected to the p-type diffusion region 15 at the end of the wafer 14 and an n-type ohmic electrode 18 on the back surface of the wafer are formed to form a light emitting diode. Here, if current is applied in the forward direction between the ohmic electrodes 17 and 18, light is emitted at a wavelength of about 660 nm from the vicinity of the pn junction.

However, the light emitting diode having the above structure can only be applied to a limited number of crystal-heavy materials.

In other words, the GaAs crystal shown in Figure 1 is 660n
Since the absorption coefficient is sufficiently large for wavelengths around m, pn
Of the light emitted near the junction, most of the original light directed laterally and downwardly is absorbed within the crystal. However, in a light emitting diode made of a semiconductor such as Qap, which has a small absorption coefficient relative to the emission wavelength, light directed laterally and downward within the crystal leaks from around the emission window either directly or through reflection and scattering.
The light emission pattern is blurred or blurred. For this reason, light emitting diode arrays and light emitting display devices may not be of practical use.

What is shown in FIG. 2 is an example of another monolithic type light emitting diode having a mesa etching structure in order to improve the above-mentioned drawbacks.

In this case, an n-type GaP layer 2 and a p-type GaP layer 22 are grown in liquid phase on the n-type GaP substrate 2o in order, and a mesa groove 23 that reaches the n-type GaP layer 21 surrounds a portion to be a light emitting region. is etched to form independent pH junctions for each light emitting region 24.24.

Then, the p-type GaP layer 22 between the light emitting regions 24 and 24
A light absorption film 25 made of, for example, a silicon film is deposited on the surface. Still, the p-type G corresponding to the light emitting region 24.24
A p-type ohmic electrode 26° 26 serving as an anode electrode is connected to the surface of the aP layer 22, and an n-type ohmic electrode 27 is attached to the back surface of the wafer, that is, the n-type GaP substrate 20. In this case, I+
When energized in one direction, it emits light at a wavelength of approximately 565 nm.

In this way, when the light emitting regions are separated by mesa etching, it is possible to sufficiently reduce the blurring, blurring, and optical crosstalk of the light emission and turns, regardless of the absorption coefficient of the crystal.

However, when forming a pn junction using a YC liquid phase growth layer as in the apparatus shown in Fig. 2, it is necessary to make the mesa groove as deep as 20 μm or more, resulting in a poor yield. With deep mesa etching, it is not possible to obtain precise and minute luminescent patterns. In addition, the method of forming nine turns of the light emitting region by performing mesa etching on a wafer in which a pn junction has been formed by diffusion is compared to the method of forming nine turns of the light emitting region by selective diffusion as shown in Figure 1. [Objective of the Invention] This invention was made in view of the above points, and can be formed regardless of the magnitude of the absorption coefficient of the semiconductor crystal for emitted light. To provide a monolithic semiconductor light-emitting device which can form a fine light-emitting area pattern with a higher yield than that of a light-emitting diode and has sufficiently small blurring and blurring of the light-emitting part and optical crosstalk between the valley light-emitting parts. − is.

[Summary of the Invention] - That is, the semiconductor light emitting device according to the present invention forms a diffusion region of opposite conductivity type forming a pn junction from the surface of a semiconductor wafer of - conductivity type, and connects the first insulating film and this insulating film in order from the bottom layer. A light-opaque portion having a laminated structure of a light-opaque film formed on the film and a second insulating film covering the light-opaque film and having a light-emitting window on the diffusion region was formed on the wafer surface. It is something.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 3 (4) to (■) are diagrams showing a light emitting diode having a plurality of light emitting parts along with its manufacturing process. First, as shown in FIG. n-GaAs doped with silicon on 3θ, -,
PX (0,65<x<1) is grown in a vapor phase while gradually increasing the amount of As, and the n-GaAsP layer 31 is formed by layer 1.
-N- doped with silicon on the GaAsP layer 3
A GaA[lO,55P 0065 layer 32 is formed. Then, the surface of this n-GaA30.35PO,65 layer 32 is doped with nitrogen (2), which serves as a luminescent center.

Next, the n-type semiconductor wafer 33 formed in this way
An S l 3N4 film 34 as a first insulating film and an 18-layer 35 as a light-opaque film each having a thickness of 1000× are deposited on the surface of the wafer by high-frequency setting, and further this Ta layer PSG (')n silicate glass) as a second insulating film on 35! G s 6
is formed by CVD method. Thereafter, a diffusion window 37° 37 matching the light emitting region pattern is opened in the S 1 3N4 film 34, 18 layer 35 and PSG film 36.

Next, as shown in FIG. 3(B), only the 18 layers 35 are made of Ta.
The site is etched to a depth of about 3 μm using an etching solution that selectively dissolves the etchant, and the peripheral portion is removed.

Thereafter, this wafer 33 and Zn were vacuum sealed in a quartz angle and diffused at 700°C for 10 hours.
As shown in C), P-GaA' with a depth of about VC 6 μm
P type diffusion region 38°38 which becomes 0.55P0.65 region
form. During this diffusion process, the PSG film 36 is softened, and the PSG film 36 on the portion of the 18 layer 35 removed by side etching becomes 515N4Il! ! 3
4 and covers and insulates the Tae tank 35.

Thereafter, as shown in FIG. 3), p-type ohmic electrodes 39, . 99, and an n-type ohmic electrode 40 is deposited on the back surface of the n-GaP substrate 30. Thereafter, a process such as a sintering process is carried out to bring the respective electrodes into sufficient ohmic contact to form a light emitting diode.

When forward current is applied to the element thus formed, the p-type diffusion region 38.38 and the n-GaABO, 35P
The wavelength 63 near the pn junction with the O,65 layer 32
Red light in the vicinity of Onm is emitted, and this red emitted light is emitted to the outside of p1 through the diffusion windows 37, 37 serving as light emission windows.

In this case, the 18 layers 35 of the light-opaque film are sandwiched and insulated by the Si 6N4 film 34 and the PSG film 36, which are the first and second insulating films, respectively. Light or light scattered within the crystal is prevented from leaking from the non-light emitting region. In the device shown in ) in Figure 3, when the interval between the light emitting parts is set to 70 μm and the light emission intensity when energized is 100%, the leakage of light to adjacent light emitting windows (optical crosstalk) is approximately 7%. It became. The optical crosstalk in the conventional structure shown in FIG. 1 is about 18%, which is improved to less than half.

The final yield of the apparatus shown in FIG. 2 is still 35 pieces, but in the above embodiment it is 60 pieces, which is a significant improvement.

Note that in the above embodiment, Ga was formed as an active layer on the GaP substrate.
Although we have described the case where AsP is grown, GaP etc.
It is clear that the invention can also be applied to wafers with other semiconductor crystals.

FIGS. 4(a) to 4(b) are diagrams showing another embodiment along with its manufacturing process, and the same components as those in the previous embodiment are given the same reference numerals and their explanations will be omitted.

Reference numeral 33 in FIG. 4(A) is an n-type semiconductor wafer similar to that in the previous embodiment, and the surface of this wafer 330 is coated with 5I0 which becomes the first insulating film with a thickness of about 1,000X in the order of 9.
2 film 42 is deposited, and on this 5iO2jli film 42, a light-opaque film of Ta, 1$35, is laminated and deposited by high frequency sputtering method. Furthermore, a PSG film 36 is formed as a second insulating film on this Ta layer 35 to a thickness of about 3000×, and diffusion windows 43 and 43 are photo-etched only on the upper PSG ll1A s 6 and 18 layers 35. do.

Thereafter, as shown in FIG. 4(B), the 18 layers 35 sandwiched between upper and lower insulating films are side-etched by about 3 μm to remove Ta at the edges.

Next, as shown in FIG. 4(C), this wafer 33 is coated with Zn.
spread. In this case, 18 layers 35 and 8102 membranes 3
Number 6 is a diffusion mask! 2. Zn diffuses into the semiconductor crystal through the 5tO2 film 42 of approximately 1.000X to form p-type diffusion regions 44.44. This p-type diffusion region 44.
44, compared to the case where Zn') is diffused without passing through the 5IO2 film 42, the Zn9 degree on the surface is more than an order of magnitude lower, and therefore the rate at which light emitted near the pn junction is reabsorbed on the crystal surface is decreases and improves external light emitting efficiency.

10- Also, the PSG film 36, which becomes the second insulating film, is softened as in the previous embodiment, and a contact hole is photo-etched into the 5102 film 42 so as to cover the Ta layer 35, and the n-GaP substrate 30 is The back surface is appropriately lapped to form p-type ohmic electrodes 45.45 and n-type ohmic electrodes 46 connected to the p-type diffusion regions 44, 44 and the n-GaP substrate 30, respectively.

Here, the p-type ohmic electrodes 4.5, 45 and n
When electricity is applied between the type ohmic electrodes 46, the light emitted near the pTl junction passes through the 5102 film and forms a light emitting window A.
It radiates to the outside from the diffusion window 43.43.

In this case, as in the previous embodiment, the first insulating film is
8iO・film・light-opaque product (the laminated structure part of the 100°J film 35 and the PSG film 36 as the second insulating film becomes the light-opaque part 41, causing the light emitting pattern to blur or become blurred. prevent it from being seen.

In addition, in Example 2, the case where 1m of Ta was used as the light-opaque film was explained, but other high melting point metals such as W (tungsten) may also be used, and after performing selective diffusion to form a p-n junction, It may be a metal bridge vapor deposited film such as At, which forms a light-opaque +1n and second insulating film, or a semiconductor film, such as silicon, which absorbs emitted light. However, the first and second insulating films are also At20. , S l 3N4.
Other insulating films such as S 102 may also be used.

〔Effect of the invention〕

As described above, according to the present invention, by providing the light-opaque portion having a structure in which the light-opaque film is sandwiched between the first and second insulating films and insulated, the fine light emitting area i4 turn, which has a low yield, can be removed. To provide a monolithic semiconductor light emitting device in which blurring and blurring of a light emitting part and optical crosstalk between light emitting parts are sufficiently small, regardless of the magnitude of the absorption coefficient of emitted light of a semiconductor crystal, without performing mesa etching that cannot be formed.

[Brief explanation of drawings]

Figures 1 and 2 are cross sections showing a conventional semiconductor light emitting device.
Figure m, Figure 3 (A, 'l~Q)l are diagrams showing a semiconductor light emitting device according to an embodiment of the present invention together with the manufacturing process, and Figures 4 (A)~(D) are views showing another example of the present invention. It is a figure which shows an Example together with a manufacturing process. , 93 =-wafer, 34-: No. 15N4 film, 35-
・-Ta layer, 36.45...I) SGN, 38,
44...p-type diffusion region, 41...light-opaque portion, 42
...SiO2 film, 4θ...light emitting window. Applicant's agent Patent attorney Takehiko Suzue 13- Figure 1 Figure 2

Claims (3)

[Claims] (1) - A compound semiconductor of a conductivity type, a diffusion region of a conductivity type opposite to that of the compound semiconductor which is diffused from the surface of the compound semiconductor, and a first layer formed on the surface of the compound semiconductor including the diffusion region in order from the bottom. the light-impermeable part has a laminated structure of an insulating film, a light-impermeable film, and a second insulating film that handles the light-impermeable film, and the light-impermeable part has a light-emitting window on the diffusion region. Semiconductor light emitting device with % characteristics. (2) The semiconductor light emitting device according to claim 1, wherein the light-opaque film is a metal film or a semiconductor film. (3) The first and second insulating films are each 5i5N.
4. The semiconductor light emitting device according to claim 1 or 2, characterized in that it is constructed of either At203 or At203.