CN114864404A - A fabrication process of charge-coupled SBR device realized by three-time mask - Google Patents

Abstract

The invention discloses a manufacturing process of a charge-coupled SBR device realized by three masks, comprising: forming a thin oxide layer; forming a body region; forming a thick oxide layer as a first mask; forming a trench by photolithography; layer; forming a first polysilicon; setting a second mask, etching the first polysilicon so that its top is lower than the surface of the epitaxial layer; using the thick oxide layer between the trenches in the active region as a mask, implanting source area ions; deposit to form a first oxide layer; isotropically etch the first oxide layer downward to expose the epitaxial layer on the surface of the active area, and form an active area contact hole in the active area trench , the contact hole of the active area extends into the second polysilicon. The manufacturing process of the present invention only needs three masks to complete the entire manufacturing process, and only when the trench is formed, the first polysilicon is formed, and the metal electrode is formed, the mask needs to be set, which saves the formation of the source region and the formation of the body contact. Zone time masks, saving costs.

Description

A fabrication process of charge-coupled SBR device realized by three-time mask

technical field

The invention relates to the technical field of semiconductors, in particular to a manufacturing process of an SBR device in which charge coupling is realized by three masks.

Background technique

The fabrication process of a conventional charge-coupled SBR device is shown in FIG. 1A to FIG. 1I , including the following steps:

A substrate 1 is provided, an epitaxial layer 2 is formed on the substrate 1, and a thin oxide layer 3 is formed on the surface of the epitaxial layer 2, as shown in FIG. 1A;

A first mask is set, a trench is formed by photolithography, and the first mask is removed, and the trench includes an active region trench 4-1 and a terminal region trench 4-2, as shown in FIG. 1B ;

A field oxide layer 5 is formed in the trench, as shown in FIG. 1C ;

Fill polysilicon and etch back to form a first polysilicon 6 in the trench, as shown in FIG. 1D ;

A second mask 7 is set, the second mask 7 covers the terminal area, and the first polysilicon 6 in the active area is etched, as shown in FIG. 1E ;

The second mask 7 is removed, and the oxide layer above the first polysilicon 6 is removed, as shown in FIG. 1F ;

A gate oxide layer 9 is formed in the trench of the active region, the second polysilicon 10 is filled and etched back, and a body region 11 is formed by implantation, as shown in FIG. 1G ;

A third mask 12 is set, the third mask 12 covers the terminal region, and the source region 13 is implanted and formed in the active region, as shown in FIG. 1H ;

The third mask 12 is removed, the barrier layer 14 is formed on the surface of the device, the fourth mask is set, the body contact area contact hole 15 and the metal contact hole 17 are formed by photolithography, and the body contact area 16 is formed by injecting downward, as shown in FIG. 1I ;

The fourth mask is removed, and metal electrodes are filled and formed in the metal contact holes 17 through the fifth mask. The above-mentioned methods for forming the body contact region contact hole 15 , the metal contact hole 17 , the body contact region 16 and the metal electrode are commonly used technical means by those skilled in the art, and will not be described in detail here.

It can be known from the above steps that in the traditional manufacturing process of the charge-coupled SBR device, at least five masks are required to realize the device function.

As is known to all, the cost of setting a mask once is extremely high, and the manufacturing cost of the entire device will greatly increase each time a mask is set. Therefore, under the premise of not affecting the performance of the device, if the number of mask settings can be reduced, the fabrication cost will be greatly reduced.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a manufacturing process of a charge-coupled SBR device with three masks, so as to solve the above-mentioned technical problems.

In order to achieve the above object, the present invention provides a manufacturing process of a 3-time mask to realize the charge-coupled SBR device, comprising the following steps:

A substrate is provided, an epitaxial layer is formed on the substrate, and a thin oxide layer is formed on the surface of the epitaxial layer;

Implant down on the surface of the device and form a body region on the surface of the epitaxial layer;

A thick oxide layer is formed on the surface of the device as a first mask;

forming trenches by photolithography, the trenches include active region trenches and terminal region trenches;

forming a field oxide layer in the active region trenches and the termination region trenches;

Filling and etching polysilicon, respectively forming a first polysilicon in the active region trench and the terminal region trench;

setting a second mask, the second mask covering the terminal area, and then etching the first polysilicon in the active area trench so that the top is lower than the surface of the epitaxial layer;

thinning the field oxide layer above the first polysilicon in the active region trench, and thinning the thick oxide layer of the active region;

Using the thick oxide layer between the trenches in the active region as a mask, implant source region ions vertically downward on the surface of the epitaxial layer in the active region;

removing the field oxide layer above the first polysilicon in the active region trenches, and removing the thin oxide layer and the thick oxide layer between the active region trenches;

removing the second mask to form a gate oxide layer over the first polysilicon in the active region trench;

Filling and etching polysilicon to form a second polysilicon in the active region trench, the surface of the second polysilicon is lower than the top of the active region trench, the surface of the second polysilicon A recessed region is formed between the top of the trench in the active region;

A first oxide layer is formed by depositing on the surface of the device, and the first oxide layer above the active region trench forms a void area;

Using the contact hole self-alignment process, the first oxide layer is etched down isotropically, so that the first polysilicon in the trench in the terminal region is exposed, and the epitaxial layer on the surface of the active region is exposed. An active area contact hole is formed in the trench, and the active area contact hole extends into the second polysilicon.

Preferably, the method further includes: implanting and forming a body contact region on the surface of the epitaxial layer between the trenches in the active region.

Preferably, the method further includes: continuing to etch down, forming a contact hole in the body contact region in the epitaxial layer between the active region trenches, and the depth of the contact hole in the active region becomes deeper, and then in the body contact region A body contact region is implanted into the region contact hole and forms a body contact region.

Preferably, it is characterized in that the body contact region contact hole is formed by self-aligned etching of active region trenches.

Preferably, the method further includes: forming a metal electrode on the surface of the device, the metal electrode is in contact with the second polysilicon through the contact hole in the active region, the metal electrode covers the active region and is in contact with the body contact region, and the metal electrode is in contact with the body contact region. Overlying the termination area and in contact with the first polysilicon in the termination area.

Preferably, after the first oxide layer is formed, the recessed region is not filled.

Preferably, when the contact hole in the active region is formed, a barrier layer formed by the first oxide layer is left on the sidewall of the top of the trench in the active region to protect the channel.

Preferably, when a gate oxide layer is formed on the first polysilicon in the active region trench, the source region ions form the source region.

Compared with the prior art, the present invention has the following beneficial effects:

(1) Compared with the traditional manufacturing process, the manufacturing process of the present invention only needs 3 masks to complete the entire manufacturing process, and only when forming the trench, forming the first polysilicon and forming the metal electrode, the mask needs to be set. The film saves the mask when forming the source region and the body contact region, and saves the cost.

(2) The present invention uses the thinned thick oxide layer as a mask to implant source region ions on the surface of the epitaxial layer of the active region, thereby saving the mask when implanting source region ions.

(3) The present invention utilizes the combination of the height of the first oxide layer and the thick oxide layer to realize the self-aligned etching of the body contact region, thereby eliminating the need for a mask originally required for the formation of the body contact region. Since the body contact area adopts a self-aligned process without mask, the cell pitch of the device can be made smaller.

(4) In the present invention, when the body contact region to be implanted is formed, the active region contact hole can be formed at the same time through the design of the recessed region of the active region, which saves the step of forming a metal contact hole in the subsequent formation of the metal electrode. .

(5) The present invention utilizes the high temperature generated when the gate oxide layer is formed to realize the annealing and shaping of the ions in the source region, and the step of forming the source region by separate annealing is omitted.

Description of drawings

1A to FIG. 1I are schematic flowcharts of the manufacturing process of the charge-coupled SBR device in the prior art;

FIG. 2A to FIG. 2P are schematic flowcharts of a fabrication process of a charge-coupled SBR device with three masks according to an embodiment of the present invention.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

FIG. 2A to FIG. 2P show a manufacturing process of a charge-coupled SBR device implemented by three masks in this embodiment, including the following steps:

Step 1: As shown in FIG. 2A, a substrate 1 is provided, an epitaxial layer 2 is formed on the substrate 1, and a thin oxide layer 3 is formed on the surface of the epitaxial layer 2. In this embodiment, the thickness of the thin oxide layer 3 is 500A.

Step 2: As shown in FIG. 2B , implant downward on the surface of the device and form a body region 11 on the surface of the epitaxial layer 2 .

Step 3: As shown in FIG. 2C , a thick oxide layer 18 is formed on the surface of the device as a first mask. In this embodiment, the thickness of the thick oxide layer 18 is 7000A.

Step 4: As shown in FIG. 2D, a trench is formed by photolithography. The trench includes an active region trench 4-1 and a terminal region trench 4-2. This step retains the thick oxide layer 18 and reduces the one-time mask removal. A step of.

Step 5: As shown in FIG. 2E, a field oxide layer 5 is formed in the active region trench 4-1 and the terminal region trench 4-2. In this embodiment, the thickness of the field oxide layer 5 is 3000A.

Step 6: As shown in FIG. 2F, polysilicon is filled and etched, and a first polysilicon 6 is formed in the active region trench 4-1 and the terminal region trench 4-2 respectively, and the surface of the first polysilicon 6 is formed. Flush with the device surface.

Step 7: As shown in FIG. 2G, a second mask 7 is set up, the second mask 7 covers the terminal area, and then the first polysilicon 6 in the active area trench 4-1 is etched so that the top is lower than The surface of the epitaxial layer 2 .

Step 8: As shown in FIG. 2H, by wet etching, the field oxide layer 5 located above the first polysilicon 6 in the active region trench 4-1 is thinned, and the thick oxide layer of the active region is thinned In this embodiment, the field oxide layer 5 is thinned from the original 3000A to 500A, and the thick oxide layer of the active region is thinned from the original 7000A to 5000A.

Step 9: As shown in FIG. 2I, using the thick oxide layer 18 between the active region trenches 4-1 as a mask, implant source region ions 8 vertically downward on the surface of the epitaxial layer 2 in the active region.

Step 10: As shown in FIG. 2J, remove the field oxide layer 5 above the first polysilicon 6 in the active region trenches 4-1, and remove the thin oxide layer between the active region trenches 4-1 3 and the thick oxide layer 18, so that the epitaxial layer 2 of the active region is exposed, and the sidewalls of the active region trench 4-1 above the first polysilicon 6 are exposed.

Step 11: As shown in FIG. 2K, the second mask 7 is removed, and a gate oxide layer 9 is formed on the first polysilicon 6 in the active region trench 4-1. Since the process of forming the gate oxide layer 9 is a high temperature process, in this step, the source region ions 8 are directly annealed to form the source region 13 , and the step of separate annealing to form the source region 13 is omitted.

Step 12: As shown in FIG. 2L, polysilicon is filled and etched, and a second polysilicon 10 is formed in the active region trench 4-1, and the surface of the second polysilicon 10 is lower than the active region trench 4 -1, a recessed region 19 is formed between the surface of the second polysilicon 10 and the top of the active region trench 4-1.

Step 13: As shown in FIG. 2M, a first oxide layer 20 is deposited on the surface of the device. Due to the presence of the recessed region 19, the first oxide layer 20 above the active region trench 4-1 forms a void region 21, In this embodiment, the thickness of the first oxide layer 20 is 3500A.

Step 14: As shown in FIG. 2N, the first oxide layer 20 is etched isotropically downward, so that the first polysilicon 6 in the trench 4-2 in the termination region is exposed, and the epitaxial layer on the surface of the active region is exposed. 2 is exposed, and an active region contact hole 22 is formed in the active region trench 4 - 1 , and the active region contact hole 22 extends into the second polysilicon 10 . Due to the existence of the void region 21 , when the active region contact hole 22 is formed, the sidewall of the top of the active region trench 4 - 1 will leave a barrier layer 23 formed by the first oxide layer 20 .

Step 15: As shown in FIG. 2O, implant and form a body contact region 16 on the surface of the epitaxial layer 2 between the active region trenches 4-1.

Step 16: As shown in FIG. 2P , a metal electrode 24 is formed on the surface of the device. The metal electrode 24 is in contact with the second polysilicon 10 through the active region contact hole 22 , and the metal electrode 24 covers the active region and is in contact with the body contact region 16 Contact, the metal electrode 24 covers the termination area and is in contact with the first polysilicon 6 in the termination area.

It will be apparent to those skilled in the art that the present invention is not limited to the details of the above-described exemplary embodiments, but that the present invention may be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments are to be regarded in all respects as illustrative and not restrictive, and the scope of the invention is to be defined by the appended claims rather than the foregoing description, which are therefore intended to fall within the scope of the claims. All changes within the meaning and scope of the equivalents of , are included in the present invention. Any reference signs in the claims shall not be construed as limiting the involved claim.

In addition, it should be understood that although this specification is described in terms of embodiments, not each embodiment only includes an independent technical solution, and this description in the specification is only for the sake of clarity, and those skilled in the art should take the specification as a whole , the technical solutions in each embodiment can also be appropriately combined to form other implementations that can be understood by those skilled in the art.

Claims (6)

1. a kind of 3 times mask realizes the manufacture technology of the SBR device of charge coupling, it is characterized in that, comprise the steps: A substrate is provided, an epitaxial layer is formed on the substrate, and a thin oxide layer is formed on the surface of the epitaxial layer; Implant down on the surface of the device and form a body region on the surface of the epitaxial layer; A thick oxide layer is formed on the surface of the device as a first mask; forming trenches by photolithography, the trenches include active region trenches and terminal region trenches; forming a field oxide layer in the active region trenches and the termination region trenches; Filling and etching polysilicon, respectively forming a first polysilicon in the active region trench and the terminal region trench; setting a second mask, the second mask covering the terminal area, and then etching the first polysilicon in the active area trench so that the top is lower than the surface of the epitaxial layer; thinning the field oxide layer above the first polysilicon in the active region trench, and thinning the thick oxide layer of the active region; Using the thick oxide layer between the trenches in the active region as a mask, implant source region ions vertically downward on the surface of the epitaxial layer in the active region; removing the field oxide layer above the first polysilicon in the active region trenches, and removing the thin oxide layer and the thick oxide layer between the active region trenches; removing the second mask to form a gate oxide layer over the first polysilicon in the active region trench; Filling and etching polysilicon to form a second polysilicon in the active region trench, the surface of the second polysilicon is lower than the top of the active region trench, the surface of the second polysilicon A recessed region is formed between the top of the trench in the active region; A first oxide layer is formed by depositing on the surface of the device, and the first oxide layer above the active region trench forms a void area; The first oxide layer is etched isotropically downward to expose the first polysilicon in the trench of the termination region, and to expose the epitaxial layer on the surface of the active region, forming an active region in the trench of the active region Contact holes, the active area contact holes extend into the second polysilicon. 2. manufacturing technique according to claim 1, is characterized in that, also comprises: Body contact regions are implanted and formed on the surface of the epitaxial layer between the active region trenches. 3. The manufacturing process according to any one of claims 2, characterized in that, further comprising: A metal electrode is formed on the surface of the device, the metal electrode is in contact with the second polysilicon through the contact hole in the active region, the metal electrode covers the active region and is in contact with the body contact region, and the metal electrode covers the terminal region and is in contact with the terminal A first polysilicon contact within the region. 4. manufacturing technique according to claim 1, is characterized in that, After the first oxide layer is formed, the recessed region is not filled. 5. manufacturing process according to claim 1, is characterized in that, When the active area contact hole is formed, a barrier layer formed by the first oxide layer is left on the sidewall of the top of the active area trench. 6. manufacturing process according to claim 1, is characterized in that, The source region ions form a source region when a gate oxide layer is formed over the first polysilicon in the active region trench.

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