CN219891545U

CN219891545U - Structure to be etched and etching system

Info

Publication number: CN219891545U
Application number: CN202321118822.0U
Authority: CN
Inventors: 李大龙
Original assignee: Tongwei Microelectronics Co ltd
Current assignee: Tongwei Microelectronics Co ltd
Priority date: 2023-05-10
Filing date: 2023-05-10
Publication date: 2023-10-24
Anticipated expiration: 2033-05-10

Abstract

The utility model provides a structure to be etched and an etching system, and relates to the technical field of semiconductors. The structure to be etched comprises: a substrate; an anti-reflection coating layer positioned on the back surface of the substrate, wherein the light transmittance of the anti-reflection coating layer is smaller than that of the substrate; a device layer located on the front side of the substrate; a photoresist layer on the device layer and the substrate surface; when the structure to be etched is in an etching state, the back surface of the substrate is placed on the carrier plate. The structure to be etched and the etching system provided by the utility model have the effect of better device performance.

Description

Structure to be etched and etching system

Technical Field

The utility model relates to the technical field of semiconductors, in particular to a structure to be etched and an etching system.

Background

Photolithography (english) is an important step in the semiconductor device manufacturing process, which uses exposure and development to pattern geometric structures on a photoresist layer, and then transfers the pattern on the photomask to the substrate by an etching process.

Generally, in the exposure process, a substrate is placed on a carrier plate, and then exposure is performed using a mask. However, due to the presence of the grooves on the carrier plate, there is reflection of light during exposure, resulting in the unexposed areas being affected.

In order to solve the problem, in the prior art, a layer of anti-reflection coating is generally coated before photoresist is coated on a substrate, and the anti-reflection coating has the advantage of low light transmittance, so that light basically cannot pass through the coating, and further the problem that the bottom carrier plate reflects to influence the exposure and development effects is avoided.

However, since the anti-reflective coating layer is directly in contact with the surface of the substrate, the anti-reflective coating layer is difficult to remove when the anti-reflective coating layer is removed after patterning the wafer using the photoresist. Generally, in the removal process, if the removal time is short, the anti-reflection coating will remain; if the removal time is long, the situation that part of the device is possibly etched away can be caused, and the performance of the device is affected.

In summary, the prior art has the problems that the accuracy required is high and the performance of the device is easily affected when the anti-reflection coating is removed.

Disclosure of Invention

The utility model aims to provide a structure to be etched and an etching system, which are used for solving the problems that in the prior art, when an anti-reflection coating is removed, the required precision is high and the performance of a device is easily influenced.

In order to achieve the above object, the technical scheme adopted by the embodiment of the utility model is as follows:

in a first aspect, an embodiment of the present utility model provides a structure to be etched, where the structure to be etched includes:

a substrate;

an anti-reflection coating layer positioned on the back surface of the substrate, wherein the light transmittance of the anti-reflection coating layer is smaller than that of the substrate;

the device layer is positioned on the front surface of the substrate;

a photoresist layer on the device layer and the surface of the substrate; wherein,,

and when the structure to be etched is in an etching state, the back surface of the substrate is placed on the carrier plate.

Optionally, the anti-reflective coating has a coefficient of friction that is greater than the coefficient of friction of the substrate.

Optionally, the difference between the coefficient of friction of the anti-reflective coating and the coefficient of friction of the substrate is greater than 0.1.

Optionally, the photoresist layer comprises a positive photoresist or a negative photoresist.

Optionally, the substrate comprises a silicon carbide substrate.

Optionally, the structure to be etched further includes a surface coating, and the surface coating is located on the surface of the photoresist layer.

On the other hand, the embodiment of the utility model also provides an etching system, wherein the structure to be etched comprises:

the carrier disc and the structure to be etched;

Optionally, a first vacuum adsorption hole is formed in the carrier plate; the etching system further comprises a vacuum pump, wherein the vacuum pump is communicated with the first vacuum adsorption hole; wherein,,

when the structure to be etched is in an etching state, the carrying disc adsorbs the structure to be etched through the first vacuum adsorption.

Optionally, a groove and a second vacuum adsorption hole are arranged on the carrier plate, and the second vacuum adsorption hole is located in the groove.

Optionally, the grooves are arranged in a ring shape.

Compared with the prior art, the utility model has the following beneficial effects:

the utility model provides a structure to be etched and an etching system, wherein the structure to be etched comprises: a substrate; an anti-reflection coating layer positioned on the back surface of the substrate, wherein the light transmittance of the anti-reflection coating layer is smaller than that of the substrate; a device layer located on the front side of the substrate; a photoresist layer on the device layer and the substrate surface; when the structure to be etched is in an etching state, the back surface of the substrate is placed on the carrier plate. The anti-reflection coating provided by the utility model is arranged on the back surface of the substrate and is positioned on the different side from the device layer, so that the effect of preventing light reflection is realized, the device layer is not influenced when the anti-reflection coating is removed, and the device performance is better.

In order to make the above objects, features and advantages of the present utility model more comprehensible, preferred embodiments accompanied with figures are described in detail below.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present utility model, the drawings that are needed in the embodiments will be briefly described below, it being understood that the following drawings only illustrate some embodiments of the present utility model and therefore should not be considered as limiting the scope, and other related drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a schematic cross-sectional view of an exposure process according to the prior art.

Fig. 2 is a top view of a prior art carrier plate.

FIG. 3 is a schematic diagram of light reflection in the prior art.

Fig. 4 is a schematic cross-sectional view of a structure to be etched in the prior art.

Fig. 5 is a schematic cross-sectional view of a structure to be etched according to an embodiment of the present utility model.

In the figure:

200-substrate; 210-device layer; 220-a photoresist layer; 230-an anti-reflective coating; 300-carrier plate.

Detailed Description

For the purpose of making the objects, technical solutions and advantages of the embodiments of the present utility model more apparent, the technical solutions of the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model, and it is apparent that the described embodiments are some embodiments of the present utility model, but not all embodiments of the present utility model. The components of the embodiments of the present utility model generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations.

Thus, the following detailed description of the embodiments of the utility model, as presented in the figures, is not intended to limit the scope of the utility model, as claimed, but is merely representative of selected embodiments of the utility model. All other embodiments, which can be made by those skilled in the art based on the embodiments of the utility model without making any inventive effort, are intended to be within the scope of the utility model.

It should be noted that: like reference numerals and letters denote like items in the following figures, and thus once an item is defined in one figure, no further definition or explanation thereof is necessary in the following figures. Meanwhile, in the description of the present utility model, the terms "first", "second", and the like are used only to distinguish the description, and are not to be construed as indicating or implying relative importance.

It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions.

In the description of the present utility model, it should be noted that, directions or positional relationships indicated by terms such as "upper", "lower", "inner", "outer", etc., are directions or positional relationships based on those shown in the drawings, or those conventionally put in use in the application, are merely for convenience of description and simplification of the description, and do not indicate or imply that the apparatus or elements referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as limiting the present utility model.

Some embodiments of the present utility model are described in detail below with reference to the accompanying drawings. The following embodiments and features of the embodiments may be combined with each other without conflict.

The exposure is to project the pattern on the mask onto the photoresist through an optical system by utilizing illumination, so that the pattern transfer is realized, and the method is one of important procedures of the photoetching process in the integrated circuit manufacturing.

The general flow of the exposure process is: the photoresist is coated on the substrate, then the mask is placed on the substrate and irradiated by the light source, and the mask is provided with the corresponding pattern, so that after the step of treatment, the appointed area of the photoresist is irradiated by the light source, and the characteristics of the photoresist in the specific area are changed. The light source can be selected according to the material of the photoresist, for example, when the photoresist is a material sensitive to ultraviolet light, the light source adopts ultraviolet light, and under the irradiation of the ultraviolet light, chemical reaction can be excited, so that the image on the mask is mixed on the photoresist and stored, after development treatment, part of the photoresist is removed, and a pattern corresponding to the mask is formed.

The photoresist is divided into positive photoresist and negative photoresist, and the negative photoresist is obtained by re-etching a pattern opposite to the pattern on the mask plate on the surface of the silicon wafer; positive photoresist is used to copy the same pattern as that on mask plate onto the surface of silicon wafer. The following description will be given respectively:

referring to fig. 1, in fig. 1, reference numeral 1 denotes a substrate, 2 denotes a photoresist, 3 denotes a mask, when a photolithography process is required, a layer of photoresist is coated on the substrate first, and then a mask is placed over the substrate, wherein a corresponding pattern is provided on the mask, as shown in the figure, a region B of the mask is a pattern portion, which is a through hole, on the basis that the region B can transmit light, and the region a cannot transmit light. When the light source is used for exposure, light rays are beaten on the mask plate as shown by arrows in the figure, and as the light can pass through the mask plate in the area B, the light rays can be beaten at the area D corresponding to the photoresist as well as the light can pass through the mask plate in the area B; the area A on the mask plate is opaque, so that the area C corresponding to the photoresist is not affected by illumination. On the basis, the region D on the photoresist is subjected to chemical reaction, while the region C is not affected, and the region C or the region D of the photoresist can be removed after development treatment because the characteristics of the region C and the region C are different.

Specifically, when a positive photoresist is used, the exposed areas of the photoresist are not dissolved during development. Namely, in the developing process, the D region of the photoresist is reserved, the C region is removed, and the rest photoresist is the photoresist of the shadow part, so that the same pattern as that on the mask plate is formed. When a negative photoresist is used, the exposed areas of the photoresist are dissolved during development. Namely, in the developing process, the D region of the photoresist is removed, the C region is reserved, and the residual photoresist is the photoresist without the filling part, so that a pattern opposite to that on the mask plate is formed.

In the photolithography process, a substrate is generally placed on a carrier plate and is processed, and in order to ensure the stability of photolithography, the substrate is generally adsorbed on the carrier plate by a vacuum adsorption method. Therefore, the carrier plate is generally provided with suction holes, for example, referring to fig. 2, which shows a top view of a carrier plate in the prior art, wherein 111 represents an independent vacuum suction hole, which is connected to a vacuum pump through a channel, 113 represents a groove, 112 represents a vacuum suction hole in the groove, when a substrate is placed on the carrier plate, the vacuum suction holes 111 and 112 are utilized to firmly suck the substrate on the surface of the carrier plate, and in the photolithography process, the movement of the substrate is not easy to occur, so that the photolithography precision is improved.

However, due to the existence of the vacuum adsorption holes and the grooves, and the light emitted by the light source cannot be guaranteed to be emitted vertically downwards, the situation that the light is reflected on the vacuum adsorption holes and the grooves and acts on the photoresist in the shading area may occur. As shown in fig. 3, 110 indicates a carrier plate, 111 indicates a vacuum adsorption hole, 113 indicates a groove, light a is reflected by the groove or the vacuum adsorption hole (possibly multiple reflections, 1 reflection is only shown in the drawing), the light is beaten on a C area, and the C area is originally an area which is blocked by a mask a and cannot be received by light, but in the case of light reflection, the C area in the photoresist is also affected, so that in the developing process, a situation of a developed pattern error may occur.

In view of this, in the prior art, before coating the photoresist, an anti-reflection coating layer is coated on the substrate, as shown in fig. 4, 110 represents a carrier plate, 1 represents a substrate, 2 represents a photoresist, 4 represents a patterning device, and 5 represents an anti-reflection coating layer, which has the advantage of low light transmittance, so that light does not substantially pass through the coating layer, and on this basis, the problem of bottom carrier plate reflection affecting the exposure development effect does not occur.

By providing the anti-reflection coating, although the problem that light reflection affects the exposure effect can be solved, removal of the anti-reflection coating after exposure development is difficult. Because the anti-reflection coating is directly contacted with the patterning device, when the anti-reflection coating is removed, if the removal time is short, the anti-reflection coating can be caused to have residues on the surface of the substrate; if the removal time is long, the situation that part of the imaging device is possibly etched away can be caused, and the performance of the device is affected.

In order to solve the problems, the utility model provides a structure to be etched, and the anti-reflection coating is arranged on the back surface of the substrate, so that the purpose of removing the anti-reflection coating is realized more conveniently.

The structure to be etched provided by the utility model is exemplified as follows:

as an alternative implementation, referring to fig. 5, the structure to be etched includes:

a substrate 200; an anti-reflection coating 230 on the back side of the substrate 200; a device layer 210 located on the front side of the substrate 200; a photoresist layer 220 on the surfaces of the device layer 210 and the substrate 200; wherein, when the structure to be etched is in an etching state, the back surface of the substrate 200 is placed on the carrier plate 300.

Since the anti-reflection coating 230 is disposed on the back surface of the substrate 200 in the present utility model, the effect of preventing light from being reflected after passing through the substrate 200 to the carrier plate 300 can be also achieved; in addition, when the anti-reflection coating 230 is removed, since the patterning device and the anti-reflection coating 230 are disposed on different sides, the patterning device is not affected when the anti-reflection coating 230 is removed, and the anti-reflection coating 230 is more conveniently removed.

The applicant has found that, in the current photolithography process, since the surface of the substrate 200 is relatively smooth, when it is placed on the carrier plate 300, although it is placed at a specific position, the substrate 200 may slide, and typically, the sliding distance is less than 100nm, so that the positioning of the substrate 200 is inaccurate, and the position of exposure and development is shifted, which affects the final device performance.

By arranging the anti-reflection coating 230 on the back surface of the substrate 200, not only the removal of the crazy-reflection coating is more convenient, but also the friction force on the back surface of the substrate 200 can be increased, so that the substrate 200 is not easy to slide when being placed on the carrier plate 300, and the positioning is more accurate. Thus, as one implementation, the coefficient of friction of the anti-reflective coating 230 is greater than the coefficient of friction of the substrate 200. Optionally, the difference between the coefficient of friction of the anti-reflective coating 230 and the coefficient of friction of the substrate 200 is greater than 0.1. By selecting the anti-reflection coating 230 with a relatively large friction coefficient with the substrate 200, when the substrate 200 is placed on the carrier plate 300, the anti-reflection coating 230 contacts with the carrier plate 300, so that the friction force between the carrier plate 300 and the anti-reflection coating 230 can be increased, the substrate 200 is not easy to slide, and the photoetching precision is improved.

The substrate 200 provided by the present utility model may be a silicon carbide substrate 200, and of course, other materials of the substrate 200 may be selected, which is not limited herein. In addition, the utility model is not limited in that positive photoresist or negative photoresist can be selected for the selection of photoresist.

It should be noted that the present utility model is not limited to the material of the anti-reflective coating layer 230, for example, the anti-reflective coating layer 230 may be a polymer having a silsesquioxane (ladder or network) structure.

Furthermore, to further enhance the anti-reflection effect and prevent light from being reflected from the photoresist surface, the structure to be etched further includes a surface coating layer on the surface of the photoresist layer 220. By arranging the surface coating, light can be transmitted to the photoresist as far as possible and not reflected, so that the exposure effect is improved.

Based on the implementation manner, the embodiment of the utility model also provides an etching system, and the structure to be etched comprises the carrier disc 300 and the structure to be etched; when the structure to be etched is in an etched state, the back surface of the substrate 200 is placed on the carrier platter 300.

Wherein, the carrier plate 300 is provided with a first vacuum adsorption hole; the etching system further comprises a vacuum pump, and the vacuum pump is communicated with the first vacuum adsorption hole; when the structure to be etched is in an etching state, the carrier disc 300 adsorbs the structure to be etched through the first vacuum adsorption.

Through setting up first vacuum adsorption hole, can be with waiting to etch the firm absorption of structure on carrier plate 300, and then can realize the stability in the photoetching process.

In addition, in order to further make the stress of the structure to be etched more uniform, the carrier plate 300 is provided with a groove and a second vacuum adsorption hole, and the second vacuum adsorption hole is positioned in the groove, and optionally, the groove is arranged in a ring shape. By arranging the grooves and the second vacuum adsorption holes, when the structure to be etched is placed on the carrier plate 300, the adsorption force is more uniform, so that the adsorption force borne by the whole substrate 200 is larger, and the stability in the photoetching process is improved.

In summary, the present utility model provides a structure to be etched and an etching system, where the structure to be etched includes: a substrate 200; an anti-reflection coating 230 positioned on the back surface of the substrate 200, the anti-reflection coating 230 having a light transmittance less than that of the substrate 200; a device layer 210 located on the front side of the substrate 200; a photoresist layer 220 on the surfaces of the device layer 210 and the substrate 200; wherein, when the structure to be etched is in an etching state, the back surface of the substrate 200 is placed on the carrier plate 300. Because the anti-reflection coating 230 provided by the utility model is arranged on the back surface of the substrate 200 and is positioned on the different side from the device layer 210, the effect of preventing light reflection is realized, and meanwhile, the device layer 210 is not affected when the anti-reflection coating 230 is removed, so that the device performance is better.

The above description is only of the preferred embodiments of the present utility model and is not intended to limit the present utility model, but various modifications and variations can be made to the present utility model by those skilled in the art. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present utility model should be included in the protection scope of the present utility model.

It will be evident to those skilled in the art that the utility model is not limited to the details of the foregoing illustrative embodiments, and that the present utility model may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, the scope of the utility model being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.

Claims

1. A structure to be etched, the structure to be etched comprising:

a substrate;

the device layer is positioned on the front surface of the substrate;

2. The structure to be etched according to claim 1, wherein a coefficient of friction of the anti-reflective coating is greater than a coefficient of friction of the substrate.

3. The structure to be etched according to claim 2, wherein a difference between a coefficient of friction of the anti-reflective coating and a coefficient of friction of the substrate is greater than 0.1.

4. The structure to be etched according to claim 1, wherein the photoresist layer comprises a positive photoresist or a negative photoresist.

5. The structure to be etched according to claim 1, wherein the substrate comprises a silicon carbide substrate.

6. The structure to be etched according to claim 1, further comprising a top coating layer on a surface of the photoresist layer.

7. An etching system, wherein the structure to be etched comprises:

a carrier plate and a structure to be etched as claimed in any one of claims 1 to 6;

8. The etching system of claim 7, wherein the carrier plate is provided with a first vacuum chucking hole; the etching system further comprises a vacuum pump, wherein the vacuum pump is communicated with the first vacuum adsorption hole; wherein,,

9. The etching system of claim 7, wherein the carrier plate is provided with a trench and a second vacuum chucking hole, the second vacuum chucking hole being located within the trench.

10. The etching system of claim 9, wherein the trench is configured in a ring shape.