CN114464524A - Photolithography, lift-off process and method of manufacturing chips - Google Patents

Abstract

Embodiments of the present application relate to photolithography, lift-off processes, and methods of manufacturing chips. According to an embodiment of the present application, a method of a photolithography process includes: providing a photoresist layer on a substrate; exposing only a partial region of the upper surface of the photoresist layer twice so that regions extending from the partial region to the lower surface of the photoresist layer form upper and lower portions having different developing characteristics; and developing the twice exposed photoresist layer, wherein the upper part remains after developing, and the lower part becomes smaller in width after developing and forms a side wall approximately vertical to the substrate. The embodiment of the application also provides a stripping process and a method for manufacturing a chip, which comprise the method of the photoetching process. The photoetching and stripping process and the method for manufacturing the chip provided by the embodiment of the application can effectively solve the problems in the traditional technology.

Description

Photolithography, lift-off process and method of manufacturing chips

technical field

Embodiments of the present application generally relate to the field of semiconductors, and more particularly, to photolithography, lift-off processes, and methods for manufacturing chips.

Background technique

In the semiconductor process, the photoresist layer is often used to transfer the two-dimensional pattern on the reticle to the photoresist layer through a photolithography process, and then the two-dimensional pattern is transferred to the target layer by some processes, such as a lift-off process, and the photolithography process is used. The structure of the etched photoresist layer generally affects the formation of the target structure on the target layer.

Therefore, the present application proposes an improved lithography, lift-off process and method of manufacturing a chip.

SUMMARY OF THE INVENTION

One of the objectives of the embodiments of the present application is to provide a photolithography, lift-off process and a method for manufacturing a chip, which can effectively transfer a target pattern to the target layer by controlling the formation structure of the photoresist layer.

An embodiment of the present application provides a method for a photolithography process, which includes: providing a photoresist layer on a substrate; exposing only a partial area of an upper surface of the photoresist layer twice, so as to extend from the partial area The area to the lower surface of the photoresist layer forms upper and lower parts with different developing characteristics; and developing the photoresist layer that has been exposed twice, wherein the upper part remains after development, and the lower part is developed to have a reduced width and form a roughly perpendicular to the sidewalls of the substrate.

According to another embodiment of the present application, the above method further includes: adjusting exposure parameters so that the width of the lower portion becomes smaller after being developed and a sidewall substantially perpendicular to the substrate is formed.

According to another embodiment of the present application, the above method further includes: heating the photoresist layer before exposing.

According to another embodiment of the present application, wherein the two exposures include: performing a first exposure on the above-mentioned partial area; and performing a second exposure on the entire area of the upper surface of the photoresist layer, wherein the first exposure uses The exposure dose is less than the exposure dose used for the second exposure.

According to another embodiment of the present application, wherein the upper portion has a length of at least about 3 micrometers and a width of about 100 nanometers to 2 micrometers; and the lower portion has a length of at least about 1 micrometer and a width of about 100 nanometers to 2 micrometers. .

Another embodiment of the present application also provides a lift-off process method, which includes the above-mentioned photolithography process method.

Yet another embodiment of the present application also provides a method for manufacturing a chip, which includes the aforementioned lift-off process method.

Compared with the prior art, the photolithography, peeling process and chip manufacturing method provided by the embodiments of the present application can effectively control the formation structure of the photoresist layer, and facilitate the effective processing of the next process.

Description of drawings

Hereinafter, drawings necessary to describe the embodiments of the present application or the related art will be briefly described in order to facilitate the description of the embodiments of the present application. Obviously, the drawings in the following description are only some embodiments of the present application. For those skilled in the art, the drawings of other embodiments can still be obtained according to the structures illustrated in these drawings without creative efforts.

1-4 are schematic diagrams of a method of a lithography process according to some embodiments of the present application.

FIG. 5 is an image under a scanning electron microscope of a T-shaped structure fabricated by a photolithography process according to some embodiments of the present application.

Detailed ways

In order to better understand the spirit of the embodiments of the present application, further descriptions are given below with reference to some preferred embodiments of the present application.

Embodiments of the present application will be described in detail below. Throughout the specification of the present application, the same or similar components and components having the same or similar functions are denoted by similar reference numerals. The embodiments described herein with respect to the figures are illustrative, diagrammatic, and intended to provide a basic understanding of the present application. The embodiments of the present application should not be construed as limitations of the present application.

As used herein, the terms "substantially," "substantially," "substantially," and "about" are used to describe and account for small variations. When used in conjunction with an event or circumstance, the terms can refer to instances in which the event or circumstance occurs precisely as well as instances in which the event or circumstance occurs proximately. For example, when used in conjunction with a numerical value, a term may refer to a range of variation less than or equal to ±10% of the numerical value, such as less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, Less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%. For example, if the difference between two values is less than or equal to ±10% of the mean of the values (eg, less than or equal to ±5%, less than or equal to ±4%, less than or equal to ±3%, less than or equal to ±2%, less than or equal to ±1%, less than or equal to ±0.5%, less than or equal to ±0.1%, or less than or equal to ±0.05%), then the two values are considered to be "substantially" the same.

In this specification, unless otherwise specified or limited, relative terms such as "vertical", "side", "upper", "lower" and their derivatives (such as "upper surface", etc. etc.) should be construed as referring to directions described in the discussion or depicted in the figures. These relative terms are used for convenience of description only and do not require that the application be constructed or operated in a particular direction.

In addition, amounts, ratios, and other numerical values are sometimes presented herein in a range format. It is to be understood that such range format is for convenience and brevity, and that it is to be flexibly construed to include not only the values expressly designated as the limits of the range, but also all individual values or subranges subsumed within the stated range, as if expressly Specify each value and subrange generically.

Also, for ease of description, "first," "second," etc. may be used herein to distinguish between different operations of a process or series of processes. "First," "second," etc. are not intended to describe corresponding processes.

1-4 are schematic diagrams of a method of a lithography process according to some embodiments of the present application.

The method includes providing a photoresist layer 101 on a substrate 100 ( FIG. 1 ); exposing only a partial area 102 of the upper surface of the photoresist layer 101 twice ( FIG. 2 ) such that the upper surface of the photoresist layer 101 is exposed twice ( FIG. 2 ). Part of the area extending to the area 105 of the lower surface of the photoresist layer 101 (dotted line part in FIG. 3 ) forms the upper part 103 and the lower part 104 ( FIG. 3 ) with different developing characteristics, as shown in FIG. 2 , the part area 102 is adjacent The areas on both sides can be covered by the opaque portions 120; and the photoresist layer that has been exposed twice is developed, wherein the upper part 103 remains after development, and the lower part 104 is developed and reduced in width and formed approximately perpendicular to the substrate. sidewall 106 of 100 (FIG. 4).

As shown in FIG. 4 , the photoresist layer is developed to form a T-shaped structure with sidewalls substantially perpendicular to the substrate, thereby transforming the two-dimensional pattern on the reticle into a three-dimensional T-shaped structure of the photoresist layer. This structure will facilitate the operation of the next process. However, the traditional process technology can only form an inverted trapezoid structure at most, which limits the next process flow.

Since the photoresist material constituting the photoresist layer is usually composed of photosensitive components, resins and solvents, when the photoresist material is processed (such as light or heating), some of the components will react or generate new substances, and then The desired pattern can be obtained by removing the partial area with a developer. However, when a part of the upper surface of the photoresist layer is exposed to light, the region extending downward from the upper surface of the photoresist layer absorbs light differently, resulting in a part from the upper surface of the photoresist layer. The regions extending to the lower surface of the photoresist layer form upper and lower portions with different development characteristics.

According to some embodiments of the present application, the above method further includes: adjusting the exposure parameters so that the width of the lower portion 104 becomes smaller after development and the sidewall 106 is formed substantially perpendicular to the substrate 100 , so that the formation structure of the photoresist layer can be adjusted. Conducive to the operation of the subsequent process.

According to some embodiments of the present application, the photoresist layer 101 can be heated before exposure according to the specific characteristics of the photoresist layer, so as to remove the solvent in the photoresist layer, improve the adhesion between the photoresist layer and the substrate, and improve the photoresist layer. The mechanical scratching ability of the layer.

According to some embodiments of the present application, only a partial area 102 of the upper surface of the photoresist layer 101 may be exposed twice: a first exposure of only a partial area 102 of the upper surface of the photoresist layer 101 , a mask exposure After the partial area 102 on the photoresist layer illuminated by the light source is reacted, it is soluble in the developing solution, for example, the photosensitive component in this area is converted into carboxylic acid; After the first exposure, the solubility of the partial area 102 after the first exposure is lower than that after the second exposure due to the cross-linking reaction, and finally the partial area from the upper surface of the photoresist layer 101 extends to the photoresist Regions 105 of the lower surface of layer 101 form an upper portion 103 and a lower portion 104 with different development characteristics.

The heating before the second exposure sometimes also leads to the cross-linking reaction of the resin part at a relatively high temperature, and the carboxylic acid has a promoting effect on the cross-linking reaction, so that the cross-linking reaction of the partial area 102 is more than that of the non-exposed area 102. Much more exposure area.

According to an embodiment of the present application, according to the above method, using Merck AZ positive/negative switchable photoresist (eg AZ5214E) as the photoresist material to form the T-type structure may include:

(1) In order to make the surface on the substrate hydrophobic to enhance the adhesion between the substrate surface and the photoresist, a tackifier can be coated on substrates such as silicon-based, quartz, and sapphire;

(2) Spin coating AZ5214E on the substrate, and the glue coating speed is about 4000r/30s, so that the photoresist is evenly coated on the surface of the substrate;

(3) pre-baking the photoresist at a temperature of about 90-100° C., for example, about 95° C., and a time of about 80-100 s, for example, about 90 s;

(4) Use a mask on an exposure machine (such as MA6 contact type) to perform mask exposure on the photoresist layer, that is, only part of the photoresist layer is exposed, wherein the broadband light source can be a wavelength of about 365-420 nm , the exposure dose is about 12-30mJ/c㎡, for example, about 24mJ/c㎡;

(5) Reverse baking the photoresist layer, for example, it can be baked on a hot plate of about 100-120°C for about 60-90s, for example, it can be baked on a hot plate of about 110°C for about 60s;

(6) Flood exposure of the photoresist layer, that is to expose the entire area of the photoresist layer on the exposure machine without using a mask, the broadband light source is UV with a wavelength of about 365-420 nm, and the flood exposure dose is about 60-360mJ /c㎡, for example about 300mJ/c㎡; and

(7) The photoresist layer is placed in a developing solution, such as tetramethylammonium hydroxide (TMAH, with a concentration of about 2.38wt%). The developing time is about 40s-45s, for example, about 40s, and if necessary, hardening (for example, Heat at a temperature of about 110°C for about 90s) process.

According to some embodiments of the present application, according to the specific pattern on the reticle used for mask exposure, the T-shaped structure shown in FIG. 4 can be formed. The upper portion 103 has a width 107 of at least about 3 microns and a height 109 of about 100 nanometers to 2 microns; and the lower portion 104 has a width 108 of at least about 1 micron and a height 110 of about 100 nanometers to 2 microns.

FIG. 5 is an image under a scanning electron microscope of a T-shaped structure fabricated by a photolithography process according to some embodiments of the present application.

As shown in FIG. 5 , the T-shaped structure 201 is located above the substrate 200 , the upper part 203 has a width of about 8 microns and a height of about 300 nanometers, and the lower part 204 has a width of about 3 microns and a height of about 1.2 microns.

It should be understood that although the photoresist layer in this embodiment uses photoresist AZ5214E, this is only an exemplary embodiment for illustrating a photolithography process method provided by the present application, and should not be construed as a reference to the present application. Restrictions on the scope of protection. According to other embodiments of the present application, other similar photoresist layers can also realize the processing of the T-shaped structure based on the above method.

The photolithography process method proposed in the present application can be beneficial to the operation of the next step. Compared with the traditional inverted trapezoidal structure made by the photoresist layer, it is difficult to control the slope. Size, and graphics distortion is small, strong resistance to dry etching.

The embodiments of the present application also provide a stripping process, which can pattern the metal layer by the above-mentioned photolithography process, which is more favorable for the metal stripping process than the inverted trapezoid 105 formed by the traditional method. The metal layer can be patterned by the above lift-off process. As shown in FIG. 5 , since the T-type structure 201 is wide at the top and narrow at the bottom, during the lift-off process, since the width of the lower portion 204 is much narrower than that of the upper portion 203 , there is no metal deposited on the side of the lower portion 204 at all, and the When the photoresist material is removed, it is easy to fall off, and the metal attached to the upper part 203 will also fall off, so as to achieve the purpose of patterning the metal layer, and the pattern distortion is small.

The embodiments of the present application also provide a method for manufacturing a chip, which can realize the patterning treatment of the metal layer through the above-mentioned peeling process.

The technical content and technical features of the present application have been disclosed as above, however, those skilled in the art may still make various substitutions and modifications without departing from the spirit of the present application based on the teachings and disclosures of the present application. Therefore, the protection scope of the present application should not be limited to the contents disclosed in the embodiments, but should include various replacements and modifications that do not deviate from the present application, and should be covered by the claims of the present patent application.

Claims (8)

1. A lithographic process, comprising:

providing a photoresist layer on a substrate;

exposing only a partial region of the upper surface of the photoresist layer twice so that regions extending from the partial region to the lower surface of the photoresist layer form upper and lower portions having different developing characteristics; and

and developing the double-exposed photoresist layer, wherein the upper part is remained after the development, and the lower part is reduced in width and forms a side wall which is approximately vertical to the substrate after the development.

2. The method of claim 1, further comprising: the parameters of the exposure are adjusted so that the lower portion becomes smaller in width and forms sidewalls substantially perpendicular to the substrate after development.

3. The method of claim 1, further comprising: heating the photoresist layer before exposure.

4. The method of any of claims 1-3, wherein the two exposures comprise:

exposing the partial area for the first time; and

and carrying out second exposure on the whole area of the upper surface of the photoresist layer.

5. The method of claim 4, wherein the first exposure uses a smaller exposure dose than the second exposure.

6. The method of claim 1, wherein:

the upper portion has a width of at least about 3 microns and a height of about 100 nanometers to 2 microns; and

the lower portion has a width of at least about 1 micron and a height of between about 100 nanometers and 2 microns.

7. A lift-off process method comprising the method according to any one of claims 1-6.

8. A method of manufacturing a chip comprising the lift-off process method of claim 7.

Images