JP2009105105A - Method of manufacturing semiconductor device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a semiconductor device executing stable device separation by using selective epitaxial growth. <P>SOLUTION: In the method of manufacturing the semiconductor device manufactured by stacking a semiconductor layer on a semiconductor substrate, when the semiconductor devices on the semiconductor substrate are separated, device units to be separated are enclosed by an insulation film, and the semiconductor device is formed by stacking the semiconductor layer in the enclosure. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a semiconductor device, and more particularly to a method for separating a plurality of semiconductor devices fabricated on a substrate.

For example, when a photodiode (hereinafter referred to as PD) is manufactured, a plurality of PDs are formed on a substrate and separated for each element.
FIG. 3 is a cross-sectional view showing a conventional PD. The PD manufacturing process and separation method will be described.
Step (1) An n ⁺ -type InP layer 2 is stacked on the n-type InP substrate 1 by epitaxial growth.
Step (2) On the n ⁺ InP layer 2, for example, an InGaAs layer 3 as a light absorption layer and an InP layer 4 as a cap layer are stacked.

Step (3) An insulating film (oxide film or nitride film, not shown) is formed on the InP cap layer 4 and patterned by photolithography, and the oxide film is partially etched with hydrofluoric acid or the like.
Step (4) Next, for example, diffusion of Zn or the like is performed, and a P ⁺ type layer 5 is formed in the portion etched in Step (3).

Step (5) The insulating film formed in the step (3) is removed, a new insulating film (not shown) is formed, and patterning is performed by photolithography to separate the elements. Thereafter, mesa etching is performed by etching or wet etching to form the groove 6.
Step (6) The insulating film formed in step (5) is removed, and a nitride film (not shown) as an antireflection film is formed on the substrate surface.

Step (7) The nitride film formed in step (6) is removed, an insulating film is formed, and then patterned by photolithography to form an electrode 7a on the substrate surface.
Step (8) The insulating film formed in step (7) is removed, and a new insulating film 8 is formed. Then, patterning is performed by photolithography, and a polyimide film 9 or the like is used on the semiconductor surface to form a mesa in step (5). The etched groove 6 is filled.
Step (9) An electrode 7b is formed on the back surface of the substrate.

  The following documents are known as prior art relating to such a method of manufacturing a semiconductor element.

JP 07-326633 A Japanese Patent Laid-Open No. 08-236611 Japanese Patent Laid-Open No. 11-074341

In the meantime, in the method of manufacturing a semiconductor device as shown in FIG. 3, there are the following problems when the mesa is formed.
That is, when mesa etching is performed by wet etching, variation in depth tends to increase in the wafer surface.
In addition, the mask must be designed in consideration of side etching. At the same time, side etching limits the chip size.

  On the other hand, when mesa etching is formed by dry etching, it can be processed according to the mask dimensions, but damage to the semiconductor surface that causes leakage current may remain. After mesa processing, an insulating film is formed on the portion to stabilize the semiconductor surface. However, depending on the film forming apparatus, a coverage problem occurs and film formation unevenness occurs.

  The film formation unevenness gives stress to the surface of the semiconductor substrate, and as a result, the leakage current may increase. For this reason, it is difficult and dangerous to bury this portion only with a thick oxide film after mesa etching.

  In addition, it is necessary to bury the mesa groove portion 6 for flattening. However, a liquid organic film such as a polyimide film or an OCD (OHKA Chemical Deposition) film is applied to the surface and baked. It is hardened by doing. These films may generate cracks and the like. In addition, these films are generally less resistant to humidity than oxide films and the like, so that leakage current is increased.

  Further, in element isolation by mesa etching, a mixed solution of hydrochloric acid, hydrogen peroxide, sulfuric acid, phosphoric acid or the like is used with an insulating film as a mask. For this reason, the selectivity varies from film to film, so that the etching solution needs to be changed.

  Accordingly, an object of the present invention is to realize a method of manufacturing a semiconductor device that can perform more stable device isolation by using selective epi without using mesa etching.

  The present invention has been made to solve the above-described problems. In the invention of the method for manufacturing a semiconductor element according to claim 1, in the method for manufacturing a semiconductor element in which a semiconductor layer is formed on a semiconductor substrate, When separating the semiconductor elements on the semiconductor substrate, the element unit to be separated is previously enclosed by an insulating film, and a semiconductor element is formed by stacking semiconductor layers in the enclosure.

In Claim 2, in the manufacturing method of the semiconductor element of Claim 1,
In forming the electrodes on the semiconductor element, the insulating film is partially etched to form a plurality of electrodes on the same surface.

In Claim 3, In the manufacturing method of the semiconductor optical element of Claim 1 or 2,
The insulating film is an oxide film or a nitride film.

In Claim 4, In the manufacturing method of the semiconductor optical element in any one of Claims 1 thru | or 3,
The semiconductor element includes a photodiode.

As is apparent from the above description, according to claims 1, 3 and 4 of the present invention, the following effects can be obtained.
When separating the semiconductor elements on the semiconductor substrate, the element unit to be separated is enclosed in advance by an insulating film, and the semiconductor layer is stacked in the enclosure to form the element, so that the number of processes can be greatly reduced by performing selective epitaxial. In addition, the leakage current characteristics of the element can be improved by separating the elements with a stable oxide film.

  According to the second aspect, since the insulating film is etched and a plurality of electrodes are formed on the same surface, the degree of freedom in incorporating the semiconductor element is improved.

1A to 1D show an example of an embodiment of a method for manufacturing a semiconductor device of the present invention. It demonstrates according to a process. Here, a case where a PD is manufactured will be described.
Step (a) Formation / patterning of insulating film (oxide film or nitride film) A Si oxide film is formed on a heated n-type Inp substrate 1 by plasma decomposition of a mixed atmosphere of SiH ₄ and N ₂ O, and the oxidation The film is patterned by photolithography and etched with hydrofluoric acid or the like to form an element unit enclosure 10 to be separated.

Step (b) Epitaxial Growth The Inp substrate 1 is heated to several hundred degrees Celsius with the enclosure (Si oxide film) 10 remaining on the substrate. Thereafter, for example, trimethylindium, trimethylgallium, arsine, and phosphine are flown, and an n ⁺ -type Inp epilayer 11, an InGaAs layer 12 serving as a light absorption layer, and an Inp layer 13 as a cap layer are formed on the substrate by epitaxial growth or the like.

  In this case, InP and InGaAs do not grow on the Si oxide film 10. That is, since the Si oxide film has a very stable bond at the temperature at which InP or InGaAs grows, no bond is taken out. For this reason, they do not stay on the Si oxide film 10 but “flow on the surface” and reach the place where the n-type Inp substrate is exposed and grow. As a result, an epitaxial film is selectively grown only on the surface of the Inp substrate 1.

Step (c) p ⁺ type layer formation An insulating film is formed on the surface of the substrate, patterned by photolithography, and the substrate masked by the insulating film and partially exposed to the Inp layer 13 as a cap layer is exposed in an atmosphere such as dimethyl zinc. Then, diffusion of Zn or the like is performed to form a p ⁺ type layer 14 as a light receiving portion.

Step (d) Antireflection Film / Electrode Formation The substrate surface is covered with an antireflection film (for example, a nitride film) or the like, and a contact hole is formed in a part of the light receiving portion p ⁺ type layer 14. An electrode 15a is formed on that portion, and an electrode 15b is also formed on the back surface of the substrate.
According to the manufacturing method described above, the number of steps can be greatly reduced by performing selective epitaxial, and the device can be improved in leakage current characteristics by separating the devices with a stable oxide film (enclosure) 10.

FIG. 2A to FIG. 2D show an example of another embodiment, which is different from FIG. 1 in that a semi-insulating InP substrate 16 is used as a substrate and n ⁺ -type InP 17 is epitaxially grown on the surface of the substrate 16. The difference is that the electrode 15c is provided on the surface side of the substrate. Here, a case where a PD is manufactured will be described.

Step (a) Formation / Patterning of Insulating Film (Oxide Film or Nitride Film) An n ⁺ type InP 17 is epitaxially grown on the surface of the semi-insulating InP substrate 16, and this substrate is heated to form SiH ₄ and N ₂ on the n ⁺ type InP 17. An Si oxide film is formed by plasma decomposition of the mixed atmosphere of O, the oxide film is patterned by photolithography, and etched with hydrofluoric acid or the like to form an element unit enclosure (Si oxide film) 10 to be separated. .

Step (b) Epitaxial Growth The semi-insulating Inp substrate 16 is heated to several hundred degrees Celsius with the enclosure (Si oxide film) 10 remaining on the substrate. Then, for example, trimethyl indium and trimethyl gallium, arsine, Inp layer as InGaAs layer 12 and the cap layer serving as the ^{n +} -type Inp epitaxial layer 11 and the light-absorbing layer on the ^{n +} -type Inp epi layer 17 on the substrate 16 flowing phosphine 13 is formed by epitaxial growth or the like.

Step (c) p ⁺ type layer formation An insulating film is formed on the surface of the substrate, patterned by photolithography, and the substrate masked by the insulating film and partially exposed to the Inp layer 13 as a cap layer is exposed in an atmosphere such as dimethyl zinc. Then, diffusion of Zn or the like is performed to form a p ⁺ type layer 14 as a light receiving portion.

Step (d) Antireflection film / electrode formation The substrate surface is covered with an antireflection film (for example, a nitride film) or the like, and contact holes are formed in a part of the light receiving portion p ⁺ layer 14 and a part of the enclosure (Si oxide film) 10. . Electrodes 15a and 15c are formed in these portions.
According to such a configuration, since there is an electrode on one surface of the semi-insulating substrate 16, the degree of freedom when incorporating the semiconductor element can be improved.

  The foregoing description is merely illustrative of certain preferred embodiments for purposes of explanation and illustration of the invention. For example, in the embodiment, a PD is manufactured as a semiconductor element. However, for example, a transistor may be used. In short, a semiconductor element to be separated is formed by stacking semiconductor layers in a prefabricated enclosure. That's fine.

  In the embodiment, an n-type Inp substrate or a semi-insulating Inp substrate is used as the substrate. However, for example, a Si substrate may be used. Therefore, the present invention is not limited to the above-described embodiments, and includes many changes and modifications without departing from the essence thereof.

It is a schematic process drawing which shows an example of embodiment of the manufacturing method of the semiconductor element of this invention. It is a schematic process drawing which shows other embodiment. It is sectional drawing which shows an example of the conventional semiconductor element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 n-type InP substrate 2,11 n-type InP epitaxial layer 3 Light absorption layer 4 Cap InP layer 5 p ⁺ layer 6 Groove 7,15 Electrode 8,10 Insulating film (oxide film or nitride film)
9 Polyimide film 12 Light absorption layer (InGaAs)
13 Cap InP layer

Claims (4)

  In a method for manufacturing a semiconductor element, in which a semiconductor layer is stacked on a semiconductor substrate, the semiconductor element on the semiconductor substrate is separated by surrounding an element unit to be separated with an insulating film in advance. A method for manufacturing a semiconductor element, comprising stacking to form a semiconductor element.   2. The method of manufacturing a semiconductor element according to claim 1, wherein, when forming an electrode on the semiconductor element, the insulating film is partially etched to form a plurality of electrodes on the same surface.   3. The method of manufacturing a semiconductor optical device according to claim 1, wherein the insulating film is an oxide film or a nitride film.   4. The method of manufacturing a semiconductor optical device according to claim 1, wherein the semiconductor device includes a photodiode.

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