JPH02192166A - Manufacture of semiconductor device - Google Patents

Abstract

PURPOSE:To protect an amorphous silicon film which grows on a lower electrode against cracks by a method wherein the lower electrode which serves as a pixel electrode is separated corresponding to pixels, and amorphous silicon is made to grow thereon. CONSTITUTION:A wiring section is formed of a WSi film 17, and a PSG film 18 is deposited as a flattening layer. Pixel electrodes are formed on the PSG film 18 through sputtering. Then, resist is applied and a specified pixel pattern is formed through a standard technique, and Ar ions are implanted through an ion implantation method using the formed pixel pattern of resist as a mask. A part 26 where Ar ions have been implanted becomes an insulating layer. Next, the resist is removed and an amorphous silicon layer 20 is formed, and a process follows, where ITO is deposited through sputtering for the formation of a transparent electrode 21. By this setup, steps are prevented from being formed on the surface of a semiconductor device of this design and cracks are also prevented from occurring in it.

Description

[Detailed Description of the Invention] [Summary] Regarding a method for manufacturing a semiconductor device, particularly a method for forming a lower electrode of amorphous silicon used in a stacked solid-state image sensor, the lower electrode (conductive film) that becomes a pixel electrode is formed into individual layers. The purpose of this invention is to provide a method for preventing cracks from occurring in the amorphous silicon film grown on the lower electrode when separating it corresponding to the pixel and growing amorphous silicon on it. In manufacturing a solid-state imaging device including a step of growing an amorphous silicon layer, a pixel electrode (19a) is formed from an oxide superconducting film, and the pixel electrode (19a) is
) includes a method for manufacturing a semiconductor device, characterized in that an insulating layer is formed by an ion implantation method corresponding to a pixel.

[Industrial use decomposition]

The present invention relates to a method of manufacturing a semiconductor device, and particularly to a method of forming a lower electrode of amorphous silicon used in a stacked solid-state image sensor.

[Prior Art] In recent years, there has been a demand for high-quality image pickup devices that have a fast photoresponse and are free from image quality defects. This requires low electrode resistance and the growth of a uniform amorphous silicon film free of defects.

A conventional stacked solid-state image sensor is shown in cross-section in FIG.
In the figure, 11 is, for example, a p-type silicon substrate, 12 and 13 are diffusion layers formed by diffusing p-type and n+-type impurities, respectively, and 14 and 15 are polycrystalline silicon electrodes of the first and second layers. , 16 is a phosphorus glass (PSG) film serving as an interlayer insulating film,
17 is a tungsten silicide (WS i ) film;
18 is a pscIg which becomes a flattening layer, 19 is an aluminum pixel electrode (conductive film), 20 is an amorphous silicon (a-5i) layer, 21 is an ITO (indium tin oxide) transparent electrode, and 22 is an ITO (indium tin oxide) transparent electrode. CCD for vertical transfer
(Charge Coupled Device)
23 is a storage diode, and 24 is a 5iOz film.

In the device shown in FIG. 2, the pixel electrode 19, which is the lower electrode of the amorphous silicon layer 20, is formed by depositing a conductive film (for example, an A°C film) on the flattening layer 18, and then etching it to form individual pixels. are formed separately in response to the In FIG. 2, reference numeral 27 indicates a connection portion between the W Si film 17 and the pixel electrode 19.

[Problems to be Solved by the Invention] If the edge portion that remains without being removed by etching is formed at an acute angle in the etching of the pixel electrode 19 described above, the amorphous silicon layer grown on the pixel electrode 19 will be damaged at this edge portion. A crack shown with numeral 25 in the figure occurs,
This crack 25 causes a pixel defect that appears white in the image.

It has been confirmed that in order to prevent the occurrence of rack 25, it is sufficient to prevent the edges of the etched portion of the pixel electrode from becoming sharp. is being done. One way is to taper the edges to be etched, and experiments have been conducted on etching methods for this purpose, but etching in a tapered shape increases the number of steps, and even with a taper, cracks may occur. Currently, it is not possible to completely prevent the occurrence of.

Another attempt is to bury the parts removed by etching with an insulating material, but this method also requires a large number of steps and is difficult to work with, and also has the problem that it cannot prevent the occurrence of cranks. There is.

Therefore, in the present invention, when a lower electrode (conductive film) that becomes a pixel electrode is separated corresponding to each pixel and amorphous silicon is grown on it, a crank occurs in the amorphous silicon film grown on the lower electrode. The purpose is to provide a method to prevent this.

[Means to solve the problem]

The above problem is solved by forming a pixel electrode using an oxide superconducting film, and applying ion implantation method to the pixel electrode corresponding to the pixel in the manufacturing of a solid-state image sensor that includes a step of growing an amorphous silicon layer on the pixel electrode. The present invention is solved by a method for manufacturing a semiconductor device characterized by forming an insulating layer using the following methods.

[Effect]

That is, since the present invention does not use etching as in the prior art when separating the lower electrode into individual pixel electrodes, no step is formed on the surface of the lower electrode on which amorphous silicon is deposited, and the amorphous silicon layer is free from cracks. This eliminates the occurrence of pixel defects due to cranking.

〔Example〕

Hereinafter, the present invention will be specifically explained with reference to illustrated embodiments.

FIG. 1 is a cross-sectional view of an embodiment of the present invention, and the same parts as those shown in FIG. 2 are denoted by the same reference numerals.

In the method of the present invention, as in the conventional example shown in FIG.
A 2n+ type scattering layer 13 is formed, thereby forming a C0D 22 for vertical transfer and a storage diode 23, and a 5in2 film 24 is formed on the surface of the silicon substrate 11 by thermal oxidation.

Next, electrodes made of a first polycrystalline silicon layer 14 and a second polycrystalline silicon layer 15 are formed, and then a PSG film 16 is deposited as an interlayer insulating film.

Next, a wiring part is formed using the WSi film 17, and P is used as a planarization layer.
SG film 18 is deposited. The steps up to this point are the same as the conventional method.

A pixel electrode is sputtered onto this PSG film 18 whose surface is flat. For example, ErBa-C is used as a sputtering target.
u (erbium-barium-copper) alloy (Er: B
a:Cu=1:2.42:3.66) at a temperature of 650°C, Ar+(h(Ar:
20%, oz: 4o%), 6 Xl0-'Tor
A pixel electrode 19a having a thickness of 3,000 layers was formed in an atmosphere of R.

Next, a resist (not shown) is applied, a predetermined pixel pattern is formed using a conventional technique, and the pixel pattern of the resist thus created is used as a mask to perform A by ion implantation.
r ions were implanted. The meter ion has an accelerating voltage of 5QKeV
The injection was performed at a dose of 5 x 10 sheets and 7 cm1. Part 2 where Ar ions were implanted by this ion implantation
No. 6 exhibited a specific resistance of 10 12 to 10 13 Ω·cm, and it was confirmed that the insulating layer had sufficient insulation properties.

Next, the resist is removed, and an amorphous silicon layer 20 is formed by depositing amorphous silicon to a thickness of 1 μm using a conventional plasma CVD device (chemical vapor deposition device), and then ITO is deposited to a thickness of 200 μm by a sputtering method.
The transparent electrode 21 was formed by depositing it to a thickness of 0.03 mm.

In the image sensor formed as described above, no white line indicating a crack in the amorphous silicon was observed in the image.
It was confirmed that since no etching was performed on the pixel electrode 19a, no step was formed on its surface, and the occurrence of cracks was prevented.

〔Effect of the invention〕

As described above, according to the present invention, there is no step on the surface of the pixel electrode to which amorphous silicon is deposited, and therefore, no crank occurs inside the amorphous silicon layer.
An image sensor with good image quality and no defects was formed, and in addition, since the pixel electrode was made of a superconductor, an image sensor with low resistance and fast response was obtained.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of an embodiment of the present invention. FIG. 2 is a sectional view of a conventional example. In the figure, 11 is a silicon substrate; 12 is a p-type scattered layer 13 is n''' type diffusion Layer 4 is a first layer of polycrystalline silicon, 15 is second layer polycrystalline silicon; 16 is a PSG film, 17 is a WSi film, 18 is a PSG film, 19 and 19a are pixel electrodes, 20 is an amorphous silicon layer, 21 is a transparent electrode; 22 is a CCD for vertical transfer; 23 is a storage diode, 24 is a SiO□ film, 25 is crack, 26 is an insulating layer shows. 25-Kura Nku 26--person color-kubon

Claims (1)

[Claims] In manufacturing a solid-state imaging device that includes a step of growing an amorphous silicon layer on a pixel electrode, a pixel electrode (19a) is formed of an oxide superconducting film, and the pixel electrode (19a) is
) A method for manufacturing a semiconductor device, comprising forming an insulating layer corresponding to a pixel by an ion implantation method.