Method for improving substrate height detection success rate in electron beam exposure process

Abstract

The invention discloses a method for improving the success rate of substrate height detection in an electron beam exposure process, which belongs to the technical field of semiconductor technologies and comprises the following steps: S1, spin-coating photoresist on the upper surface of a substrate and baking; s2, spin-coating a water-soluble conductive adhesive with the thickness of k1 on the upper surface of the photoresist; s3, depositing a metal layer with the thickness of k2 on the upper surface of the water-soluble conductive adhesive; 10 nm < = k2 < = 30 nm; k1 > = 2k2; s4, electron beam exposure; detecting the height of the substrate in the electron beam exposure process; s5, removing the water-soluble conductive adhesive and the metal layer; and S6, developing and fixing. The method comprises the following steps of: spin-coating a layer of water-soluble conductive adhesive on the surface of a substrate which is normally spin-coated with photoresist, and then depositing a layer of metal film; the method can well improve the success rate of substrate height detection in the electron beam exposure process.

Description

Technical Field

[0001] The invention belongs to the technical field of semiconductor process, and in particular relates to a method for improving the success rate of substrate height detection in an electron beam exposure process. Background Art

[0002] Electron beam lithography (EBL) plays a vital role in the field of micro-nano processing, micro-nano optoelectronic chip manufacturing, and integrated circuit production. The core of this technology is to use a focused electron beam to accurately write the required micro-nano structure pattern directly on the electron-sensitive material. Its significant advantage lies in its ultra-high resolution, and the limit size can be less than 10 nanometers, which makes it unparalleled in micro-nanoscale processing. In addition, EBL also has flexible graphics drawing capabilities, that is, direct writing function, without the need for pre-preparation of masks, which greatly improves production efficiency and flexibility. Due to its unique advantages, electron beam lithography has been widely used in the production of imprint masters and photolithography masks, nano-level scientific research and development, and the manufacturing process of advanced prototypes. In these applications, EBL can achieve precision and complexity that other traditional lithography technologies cannot achieve, thereby promoting the rapid development of micro-nano technology.

[0003] However, during the electron beam exposure process, in order to correct the focus change and electron beam deflection error caused by the height difference of the substrate surface, the height detection of the substrate surface must be performed. This detection mechanism usually uses CCD (charge coupled device) to capture the change in the position of the pattern after the light of a specific wavelength is reflected on the substrate surface, thereby reflecting the height change. In this way, the accuracy and consistency of electron beam lithography can be ensured, thereby ensuring the quality of the final product.

[0004] However, for some material substrates that are translucent at specific wavelengths, this height detection method cannot be effectively implemented. This is because light of a specific wavelength will penetrate these materials, causing the reflected signal to weaken or disappear, making it impossible to accurately capture the changes in the position of the pattern. The existence of this situation hinders the smooth progress of the electron beam exposure process and limits its application range on certain specific materials. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for improving the success rate of substrate height detection in the electron beam exposure process. On the surface of the substrate on which the photoresist is normally spin-coated, a layer of water-soluble conductive glue is first spin-coated, and then a layer of metal film is deposited; this method can well improve the success rate of substrate height detection in the electron beam exposure process.

[0006] The technical solution adopted by the present invention is:

[0007] A method for improving the success rate of substrate height detection in an electron beam exposure process, comprising:

[0008] S1, spin coating photoresist on the upper surface of the substrate and baking;

[0009] S2, spin coating a water-soluble conductive adhesive with a thickness of k1 on the upper surface of the photoresist;

[0010] S3, depositing a metal layer with a thickness of k2 on the upper surface of the water-soluble conductive adhesive; 10nm≤k2≤30nm; k1≥2k2;

[0011] S4, electron beam exposure; detecting the height of the substrate during the electron beam exposure process;

[0012] S5, removing the water-soluble conductive glue and the metal layer;

[0013] S6, developing and fixing.

[0014] Preferably, the substrate is made of a light-transmitting material.

[0015] Preferably, the substrate is a sapphire substrate, or a quartz substrate, or a glass substrate, and the metal layer is a chromium metal film or an aluminum metal film.

[0016] Preferably, the thickness of the water-soluble conductive adhesive is 30 nm.

[0017] Preferably, the thickness of the metal layer is 15 nm.

[0018] Compared with the prior art, the advantages and positive effects of this application are:

[0019] The present invention spin-coats a layer of water-soluble conductive glue with a thickness of k1 on the substrate surface on which the photoresist has been normally spin-coated, and then deposits a layer of metal film with a thickness of k2. Since the metal is opaque to the light used for height detection, the height detection process of the substrate surface can be normally implemented. In addition, the spin-coated conductive glue has a water-soluble property, so that after the exposure operation is completed, the conductive glue and the metal film covering it can be effectively removed by only immersing the entire substrate in deionized water.

[0020] The present invention not only realizes the height detection and electron beam exposure functions of the light-transmitting substrate, but also has simple operation steps and does not cause adverse effects on the accuracy of the electron beam exposure. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 This is a process flow chart of a preferred embodiment of the present application. DETAILED DESCRIPTION

[0023] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely represents the selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without making creative work belong to the scope of protection of the present invention.

[0024] See also Figure 1 , a method for improving the success rate of substrate height detection in an electron beam exposure process, comprising:

[0025] S1. Spin-coat a layer of photoresist uniformly on the upper surface of the substrate, and then perform baking treatment; the substrate mentioned in this application mainly refers to those substrates of specific materials that can transmit light at a specific wavelength, such as a sapphire substrate, or a quartz substrate, or a glass substrate, etc., and the metal layer is a chromium metal film or an aluminum metal film, etc.

[0026] S2, spin coating a water-soluble conductive adhesive with a thickness of k1 on the upper surface of the photoresist;

[0027] S3, depositing a metal layer with a thickness of k2 on the upper surface of the water-soluble conductive adhesive; the metal layer may be a chromium metal film;

[0028] Regarding the thickness k2 of the metal layer, its range needs to be strictly controlled to ensure that it is not too thin to reflect the light at the detection height, but also too thick to aggravate the forward scattering effect of the electron beam, thereby affecting the exposure accuracy. Specifically, the thickness k2 of the metal layer needs to meet the following conditions: 10nm≤k2≤30nm. At the same time, the thickness k1 of the water-soluble conductive adhesive needs to be twice or more than the thickness k2 of the metal layer to ensure that the metal film can be smoothly peeled off in a deionized water solution environment as the conductive adhesive dissolves, that is, k1≥2k2 needs to be satisfied;

[0029] S4, electron beam exposure; detecting the height of the substrate during the electron beam exposure process;

[0030] S5, removing the water-soluble conductive glue and the metal layer;

[0031] S6, developing and fixing.

[0032] In order to more deeply understand the technical solution of the present invention, the following non-limiting examples are given:

[0033] The thickness of the water-soluble conductive adhesive is 30 nm.

[0034] The thickness of the metal layer is 15 nm.

[0035] The above description is only a preferred embodiment of the present invention and is not intended to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A method for improving the success rate of substrate height detection during electron beam exposure, characterized in that: include: S1, spin coating photoresist on the upper surface of the substrate and baking; S2, spin coating a water-soluble conductive adhesive with a thickness of k1 on the upper surface of the photoresist; S3, depositing a metal layer with a thickness of k2 on the upper surface of the water-soluble conductive adhesive; 10nm≤k2≤30nm; k1≥2k2; S4, electron beam exposure; detecting the height of the substrate during the electron beam exposure process; S5, removing the water-soluble conductive glue and the metal layer; S6, developing and fixing.

2. The method for improving the success rate of substrate height detection in electron beam exposure process according to claim 1, characterized in that: The substrate is made of light-transmitting material.

3. The method for improving the success rate of substrate height detection in electron beam exposure process according to claim 2, characterized in that: The substrate is a sapphire substrate, a quartz substrate, or a glass substrate, and the metal layer is a chromium metal film or an aluminum metal film.

4. The method for improving the success rate of substrate height detection in electron beam exposure process according to any one of claims 1 to 3, characterized in that: The thickness of the water-soluble conductive adhesive is 30 nm.

5. The method for improving the success rate of substrate height detection in electron beam exposure process according to claim 4, characterized in that: The thickness of the metal layer is 15 nm.

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