Photodiode and manufacturing method thereof

Abstract

The invention provides a photodiode comprising a first semiconductor type surface region; a second semiconductor type shallow surface layer formed in a portion of the first semiconductor type surface region, where an active photodiode region is formed by a PN junction of the first semiconductor type surface region and the second semiconductor type shallow surface layer, and a passivation coating is formed on the shallow surface layer; the interlayer dielectric layer covers the first semiconductor type surface area, the interlayer dielectric layer is opened to form a first opening pattern, and a first electrode is formed in the opening pattern; the interlayer dielectric layer is covered with the inter-metal insulating dielectric layer, a shading layer is formed on the inter-metal insulating dielectric layer, and a shading layer is formed on the portion, above the non-working area of the photodiode, of the inter-metal insulating dielectric layer. During illumination, interference of an external light source on a working area of the device can be avoided, so that the light response performance of the photodiode is improved.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and particularly to a photodiode and a manufacturing method thereof. Background Art

[0002] A photodiode is a semiconductor device that converts light energy into electrical energy and is mainly composed of a PN junction. When light irradiates the photodiode, the energy of photons excites electrons from the valence band to the conduction band, generating electron-hole pairs. These carriers are separated under the action of an electric field to form a photocurrent.

[0003] As a device for signal transmission, an optical encoder is widely used in fields such as industrial automation, medical treatment, energy, and aerospace. Among them, a photodiode is an important component. The light response performance of the photodiode is closely related to the high precision of the optical encoder because the photodiode has different sensitivities to light of different wavelengths. Therefore, how to avoid the interference of light in the non-working wavelength range is crucial for improving the light response performance of the photodiode.

[0004] To solve the above problems, a new type of photodiode and a manufacturing method thereof need to be proposed. Summary of the Invention

[0005] In view of the above-mentioned disadvantages of the prior art, the purpose of the present invention is to provide a photodiode and a manufacturing method thereof, which are used to solve the problem that the photodiode in the prior art is easily interfered by light in the non-working wavelength range.

[0006] To achieve the above purpose and other related purposes, the present invention provides a photodiode, including:

[0007] A first semiconductor type surface region;

[0008] A second semiconductor type shallow surface layer formed in a part of the first semiconductor type surface region, wherein an active photodiode region is formed through the PN junction of the first semiconductor type surface region and the second semiconductor type shallow surface layer, and a passivation coating is formed on the shallow surface layer;

[0009] An interlayer dielectric layer covering the first semiconductor type surface region, the interlayer dielectric layer is opened to form a first opening pattern, and a first electrode is formed in the opening pattern;

[0010] An intermetallic insulating dielectric layer covering the interlayer dielectric layer, a light-shielding layer is formed on the intermetallic insulating dielectric layer, and a light-shielding layer is formed on the intermetallic insulating dielectric layer above the non-working region of the photodiode;

[0011] A passivation layer covering the light-shielding layer and the intermetallic insulating dielectric layer, and a second opening pattern with a bottom connected to the first electrode is formed on the passivation layer.

[0012] Preferably, the first semiconductor type is one of P-type and N-type; and the second semiconductor type is the other of P-type and N-type.

[0013] Preferably, the interlayer dielectric layer includes at least one of a dielectric material of silicon oxide and a low-k dielectric material.

[0014] Preferably, the intermetallic insulating dielectric layer is composed of a high-density plasma oxidation layer and a non-infiltrating impurity silicate glass thereon.

[0015] Preferably, the material of the light-shielding layer is TiN.

[0016] Preferably, the material of the passivation layer is a plasma-enhanced oxidation layer.

[0017] Preferably, the photodiode further includes forming ion implantation and a second electrode in the back region of the first semiconductor type.

[0018] The present invention also provides a manufacturing method of the above photodiode, including:

[0019] Step 1: Form a second semiconductor type shallow surface layer in a part of the surface region of the first semiconductor type, wherein an active photodiode region is formed through the PN junction of the surface region of the first semiconductor type and the second semiconductor type shallow surface layer, and a passivation coating is formed on the shallow surface layer;

[0020] Step 2: Use deposition and grinding methods to form an interlayer dielectric layer, open the interlayer dielectric layer to form a first opening pattern, and fill the opening pattern with a metal layer to form a first electrode;

[0021] Step 3: Use deposition and grinding methods to form an intermetallic insulating dielectric layer, form a light-shielding layer on the intermetallic insulating dielectric layer, open the light-shielding layer above the photodiode region, and retain the non-working region of the light-shielding layer on the photodiode;

[0022] Step 4: Use deposition and grinding methods to form a passivation layer, open the passivation layer to form a second opening pattern with a bottom connected to the first electrode.

[0023] Preferably, in step 1, the first semiconductor type is one of P-type and N-type; and the second semiconductor type is the other of P-type and N-type.

[0024] Preferably, in step 2, the interlayer dielectric layer includes at least one of a dielectric material of silicon oxide and a low-k dielectric material.

[0025] Preferably, the inter-metal insulating dielectric layer in step three is composed of a high-density plasma oxidation layer and a non-infiltrating impurity silicate glass thereon.

[0026] Preferably, the material of the light-shielding layer in step three is TiN.

[0027] Preferably, the material of the passivation layer in step four is a plasma-enhanced oxidation layer.

[0028] Preferably, the photodiode further includes forming ion implantation and a second electrode in the back region of the first semiconductor type.

[0029] As described above, the photodiode and its manufacturing method of the present invention have the following beneficial effects:

[0030] When the present invention is irradiated with light, it can avoid interference of the external light source on the working area of the device, thereby improving the light response performance of the photodiode. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It shows a schematic process flow diagram of the present invention;

[0032] Figure 2 It shows a schematic diagram of forming the first electrode of the present invention;

[0033] Figure 3 It shows a schematic diagram of forming the light-shielding layer of the present invention;

[0034] Figure 4 It shows a schematic diagram of forming the second opening pattern of the present invention;

[0035] Figure 5 It shows a schematic diagram of comparing the device performance with and without the light-shielding layer of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0036] The following describes the embodiments of the present invention through specific specific examples. Those skilled in the art can easily understand the other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention.

[0037] Please refer to Figure 4 , the present invention provides a photodiode, including:

[0038] A surface region 101 of the first semiconductor type;

[0039] A second semiconductor type shallow surface layer 102 is formed in a part of the first semiconductor type surface region 101, wherein an active photodiode region is formed by the PN junction of the first semiconductor type surface region 101 and the second semiconductor type shallow surface layer 102, and a passivation coating 103 is formed on the shallow surface layer 102; for example, the surface region 101 is the surface of an N-type substrate. The second semiconductor type shallow surface layer 102, such as a P well, can be formed in a part of the surface region 101 to form an active PN junction photodiode region.

[0040] In some embodiments, the first semiconductor type is one of P-type and N-type; and the second semiconductor type is the other of P-type and N-type.

[0041] An interlayer dielectric layer 104 covering the first semiconductor type surface region 101 is opened to form a first opening pattern, and a first electrode 105 is formed in the opening pattern; for example, a heavily doped region 106 can be formed on the substrate surface, and the bottom end of the first electrode 105 is in contact with the heavily doped region 106;

[0042] In some embodiments, the interlayer dielectric layer 104 includes a dielectric material such as silicon oxide, a low-k dielectric material, other suitable dielectric materials, or a combination thereof. In some instances, the low-k dielectric material includes fluorinated silicon glass (FSG), carbon-doped silicon oxide, xerogel, aerogel, amorphous fluorocarbon, parylene, BCB (bisbenzocyclobutene), polyimide, and / or other suitable dielectric materials with a dielectric constant substantially less than that of thermally oxidized silicon.

[0043] An intermetallic insulating dielectric layer 109 covering the interlayer dielectric layer 104, a light-shielding layer 110 is formed on the intermetallic insulating dielectric layer 109, and a light-shielding layer 110 is formed on the intermetallic insulating dielectric layer 109 above the non-working region of the photodiode; during illumination, external light sources can be prevented from interfering with the working area of the device, thereby improving the light response performance of the photodiode.

[0044] In some embodiments, the intermetallic insulating dielectric layer 109 is composed of a high-density plasma oxide layer and a non-infiltrating impurity silicate glass thereon.

[0045] A passivation layer 111 covering the light-shielding layer 110 and the intermetallic insulating dielectric layer 109, and a second opening pattern with a bottom communicating with the first electrode 105 is formed on the passivation layer 111.

[0046] In some embodiments, the material of the light-shielding layer 110 is TiN. In other embodiments, the light-shielding layer 110 can also use light-shielding materials well-known to those skilled in the art.

[0047] In some embodiments, the material of the passivation layer 111 is a plasma-enhanced oxide layer.

[0048] In some embodiments, the photodiode further includes forming an ion implantation 108 and a second electrode 107 in the back region of the first semiconductor type. That is, an ion implantation 108 is performed on the back side of the substrate, and then the second electrode 107 is formed.

[0049] Please refer to Figure 5 , compared with the photodiode structure without the light-shielding layer 110, for the photodiode structure with the light-shielding layer 110, the dark current decreases, and the photocurrent also increases to a certain extent, and the overall light response performance is significantly improved.

[0050] The present invention also provides a manufacturing method of the above-mentioned photodiode, including:

[0051] Step 1: Form a second semiconductor type shallow surface layer 102 in a part of the surface region 101 of the first semiconductor type, wherein an active photodiode region is formed through the PN junction of the first semiconductor type surface region 101 and the second semiconductor type shallow surface layer 102, and a passivation coating 103 is formed on the shallow surface layer 102; for example, the surface region 101 is the surface of an N-type substrate. The second semiconductor type shallow surface layer 102, such as a P-well, can be formed in a part of the surface region 101, thereby forming an active PN junction photodiode region.

[0052] In some embodiments, the photodiode further includes forming an ion implantation 108 and a second electrode 107 in the back region of the first semiconductor type.

[0053] In some embodiments, the first semiconductor type in Step 1 is one of P-type and N-type; and the second semiconductor type is the other of P-type and N-type.

[0054] Step 2: Use the methods of deposition and grinding to form an interlayer dielectric layer 104. In the embodiments of the present invention, the grinding method can be chemical mechanical planarization grinding. Use photolithography and etching methods to open the interlayer dielectric layer 104 to form a first opening pattern, and fill the opening pattern with a metal layer to form a first electrode 105, forming a structure as Figure 2 shown; for example, a heavily doped region 106 can be formed on the substrate surface, and the bottom end of the first electrode 105 is in contact with the heavily doped region 106;

[0055] In some embodiments, the interlayer dielectric layer 104 in Step 2 includes at least one of a dielectric material of silicon oxide and a low-k dielectric material.

[0056] Step 3: Form an inter-metal insulating dielectric layer 109 by deposition and polishing. Form a light-shielding layer 110 on the inter-metal insulating dielectric layer 109. Use photolithography and etching methods to open the light-shielding layer 110 above the photodiode region, and retain the non-working area of the light-shielding layer 110 on the photodiode, forming a structure as shown in Figure 3 When illuminated, it can prevent external light sources from interfering with the working area of the device, thereby improving the light response performance of the photodiode.

[0057] In some embodiments, the inter-metal insulating dielectric layer 109 in Step 3 is composed of a high-density plasma oxide layer and a non-infiltrating impurity silicate glass thereon.

[0058] In some embodiments, the material of the light-shielding layer 110 in Step 3 is TiN. In other embodiments, the light-shielding layer 110 can also use light-shielding materials well-known to those skilled in the art.

[0059] Step 4: Form a passivation layer 111 by deposition and polishing. Use photolithography and etching methods to open the passivation layer 111 to form a second opening pattern with the bottom connected to the first electrode 105, forming a structure as shown in Figure 4 to form a pad for leading out the first electrode 105.

[0060] In some embodiments, the material of the passivation layer 111 in Step 4 is a plasma-enhanced oxide layer.

[0061] In some embodiments, the photodiode further includes forming an ion implantation 108 and a second electrode 107 in the back region of the first semiconductor type. That is, ion implantation 105 is performed on the back line of the substrate, and then the second electrode 107 is formed.

[0062] Please refer to Figure 5 , compared with the photodiode structure without the light-shielding layer 110, for the photodiode structure with the light-shielding layer 110, the dark current decreases, and the photocurrent also increases to a certain extent, and the overall light response performance is significantly improved.

[0063] It should be noted that the diagrams provided in this embodiment only illustrate the basic concept of the present invention in a schematic manner. Therefore, only the components related to the present invention are shown in the diagrams, rather than being drawn according to the number, shape, and size of the components in actual implementation. The types, quantities, and proportions of the components in actual implementation can be arbitrarily changed, and the component layout type may also be more complex.

[0064] In summary, when illuminated, the present invention can prevent external light sources from interfering with the working area of the device, thereby improving the light response performance of the photodiode. Therefore, the present invention effectively overcomes various disadvantages in the prior art and has high industrial utilization value.

[0065] The above embodiments are only illustrative of the principles and effects of the present invention and are not intended to limit the present invention. Any person familiar with this technology can modify or change the above embodiments without departing from the spirit and scope of the present invention. Therefore, all equivalent modifications or changes made by those with ordinary knowledge in the technical field without departing from the spirit and technical ideas disclosed by the present invention should still be covered by the claims of the present invention.

Claims

1. A photodiode, characterized in that: include: a first semiconductor type surface region; a second semiconductor type shallow surface layer formed in a portion of the first semiconductor type surface region, wherein an active photodiode region is formed by a PN junction of the first semiconductor type surface region and the second semiconductor type shallow surface layer, and a passivation coating is formed on the shallow surface layer; an interlayer dielectric layer covering the first semiconductor type surface region, opening the interlayer dielectric layer to form a first opening pattern, wherein a first electrode is formed in the opening pattern; an intermetallic insulating dielectric layer covering the interlayer dielectric layer, forming a light shielding layer on the intermetallic insulating dielectric layer, and forming a light shielding layer on the intermetallic insulating dielectric layer above the non-working area of ​​the photodiode; A passivation layer covers the light shielding layer and the intermetallic insulating dielectric layer, and a second opening pattern whose bottom is connected to the first electrode is formed on the passivation layer.

2. The photodiode according to claim 1, characterized in that: The first semiconductor type is one of a P type and an N type; and the second semiconductor type is the other of a P type and an N type.

3. The photodiode according to claim 1, characterized in that: The interlayer dielectric layer includes at least one of a silicon oxide dielectric material and a low-k dielectric material.

4. The photodiode according to claim 1, characterized in that: The intermetallic insulating dielectric layer is composed of a high-density plasma oxide layer and a silicate glass without infiltration of impurities thereon.

5. The photodiode according to claim 1, characterized in that: The material of the light shielding layer is TiN.

6. The photodiode according to claim 1, characterized in that: The material of the passivation layer is a plasma enhanced oxidation layer.

7. The photodiode according to claim 1, characterized in that: The photodiode further includes forming an ion implantation and a second electrode in a first semiconductor type backside region.

8. The method for manufacturing a photodiode according to any one of claims 1 to 7, characterized in that: At least: Step 1: forming a second semiconductor type shallow surface layer in a portion of the first semiconductor type surface region, wherein an active photodiode region is formed by a PN junction of the first semiconductor type surface region and the second semiconductor type shallow surface layer, and forming a passivation coating on the shallow surface layer; Step 2: forming an interlayer dielectric layer by deposition and grinding, opening the interlayer dielectric layer to form a first opening pattern, and filling the opening pattern with a metal layer to form a first electrode; Step 3: forming an intermetallic insulating dielectric layer by deposition and grinding, forming a light shielding layer on the intermetallic insulating dielectric layer, opening the light shielding layer above the photodiode region, and retaining a non-working region of the light shielding layer on the photodiode; Step 4: forming a passivation layer by deposition and grinding, and opening the passivation layer to form a second opening pattern at the bottom thereof connected to the first electrode.

9. The method for manufacturing a photodiode according to claim 8, characterized in that: The first semiconductor type in step 1 is one of P type and N type; and the second semiconductor type is the other of P type and N type.

10. The method for manufacturing a photodiode according to claim 8, characterized in that: The interlayer dielectric layer in step 2 includes at least one of a silicon oxide dielectric material and a low-k dielectric material.

11. The method for manufacturing a photodiode according to claim 8, characterized in that: The intermetallic insulating dielectric layer in step three is composed of a high-density plasma oxide layer and a silicate glass without impurities thereon.

12. The method for manufacturing a photodiode according to claim 8, characterized in that: The material of the light shielding layer in step three is TiN.

13. The method for manufacturing a photodiode according to claim 8, wherein: The material of the passivation layer in step 4 is a plasma enhanced oxide layer.

14. The method for manufacturing a photodiode according to claim 8, wherein: The photodiode further includes forming an ion implantation and a second electrode in a first semiconductor type backside region.

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