CN105448762A - Method for adjusting warping degree of substrate - Google Patents

Abstract

The present application discloses a method for adjusting substrate warpage. The method includes: obtaining the warpage of the substrate, wherein a first film is formed on the first surface of the substrate; judging whether the absolute value of the warpage of the substrate is greater than or equal to a warpage threshold; If so, forming an adjustment film on the second surface of the substrate so that the warpage of the substrate is less than the warpage threshold, wherein the expansion coefficient of the adjustment film is the same as that of the first film The expansion coefficients are both smaller than the expansion coefficient of the substrate, or, the expansion coefficients of the adjustment film and the first film are both greater than the expansion coefficient of the substrate; the normal direction of the first surface and The normal direction of the second surface is opposite. The method can efficiently and controllably adjust the warpage of the substrate without affecting the original substrate processing technology, thereby ensuring the performance of the product and enabling the smooth progress of the photolithography process after the thin film deposition.

Description

A method for adjusting substrate warpage

technical field

The present application relates to the technical field of semiconductor manufacturing technology, and in particular to a method for adjusting substrate warpage.

Background technique

With the rapid development of the semiconductor industry, the size of the processed substrates is also increasing. Take the processing of silicon wafers as an example. At present, 12-inch silicon wafers have become the mainstream. In the next few years, even 15-inch silicon wafers will appear. However, the larger the size of the silicon wafer, the easier it is to highlight the warpage of the silicon wafer, such as a film-coated silicon wafer with a thin film deposited on the surface. Bowvalue is usually used to measure the warpage of silicon wafers. The warpage of silicon wafers can be divided into positive and negative points. When the silicon wafer is bent towards the film, the warpage is positive, and when the silicon wafer is bent away from the film, Its warpage is negative.

In several processing techniques for silicon wafers, it is necessary to use a series of actions such as loading with high-precision robotic arms, and if the warping of the silicon wafers is too large, the robotic arms may not be able to hold the silicon wafers and cause Can't work on it.

When this happens, the usual method is to adjust the previous silicon wafer processing technology, such as adjusting the thickness or type of deposited film, or adjusting the process sequence, etc., and many experiments are required until the robot arm works smoothly. . However, this method is inefficient, and changes in the process may have unknown effects on the final product, such as reduced product performance.

Contents of the invention

In order to solve the above technical problems, the embodiment of the present application provides a substrate warpage adjustment method, which can controllably adjust the substrate warpage efficiently without affecting the original substrate processing technology. The technical scheme is as follows:

A method for adjusting substrate warpage, comprising:

Obtaining the warpage of the substrate, wherein the first film is formed on the first surface of the substrate;

judging whether the absolute value of the warpage of the substrate is greater than or equal to the warpage threshold;

If so, forming an adjustment film on the second surface of the substrate so that the warpage of the substrate is less than the warpage threshold, wherein the expansion coefficient of the adjustment film is the same as that of the first film The expansion coefficients are both smaller than the expansion coefficient of the substrate, or, the expansion coefficients of the adjustment film and the first film are both greater than the expansion coefficient of the substrate; the normal direction of the first surface and The normal direction of the second surface is opposite.

Further, the warpage threshold is 200 microns.

Further, the substrate is a silicon wafer.

Further, the adjustment film is a high tensile stress film or a high pressure stress film.

Further, the adjustment film is a silicon nitride film, a titanium nitride film or a tungsten metal film.

Embodiments of the present invention at least have the following beneficial effects:

In this embodiment, the degree of warpage of the substrate is corrected or adjusted by forming an adjustment film on the substrate, thereby reducing the degree of warpage of the substrate, so that the robotic arm can hold the substrate and load it, etc. Operation. The method can efficiently and controllably adjust the warpage of the substrate without affecting the original substrate processing technology, thereby ensuring the performance of the product and enabling the smooth progress of the photolithography process after the thin film deposition.

Description of drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments described in this application. Those skilled in the art can also obtain other drawings based on these drawings without creative work. The following drawings are not deliberately scaled and drawn according to the actual size, and the emphasis is on illustrating the gist of the present application.

FIG. 1 is a flow chart of a method for adjusting substrate warpage according to an embodiment of the present invention;

Figure 2a is a schematic structural view of forming a first thin film on a substrate;

Fig. 2b is a schematic structural diagram of the substrate shown in Fig. 2a shrinking to positive warpage after forming the first film;

Fig. 2c is a schematic structural diagram of the substrate shown in Fig. 2a shrinking to a negative warpage after forming the first film;

Figure 3a is a schematic structural view of forming an adjustment thin film on the substrate shown in Figure 2b;

Fig. 3b is a schematic structural diagram of forming an adjustment thin film on the substrate shown in Fig. 2c.

detailed description

In order to make the above objects, features and advantages of the present invention more comprehensible, specific implementations of the present invention will be described in detail below in conjunction with the accompanying drawings.

In the following description, many specific details are set forth in order to fully understand the present invention, but the present invention can also be implemented in other ways than those described here, so the present invention is not limited by the specific embodiments disclosed below.

Secondly, the present invention is described in detail in conjunction with schematic diagrams. When describing the embodiments of the present invention in detail, for the convenience of explanation, the sectional view showing the structure of the device will not be partially enlarged according to the general scale, and the schematic diagram is only an example, and it should not be limited here. The protection scope of the present invention. In addition, the three-dimensional space dimensions of length, width and depth should be included in actual production.

In the prior art, one of the reasons for the warping of the substrate is that when the film is deposited on the substrate at high temperature, both the film and the substrate will shrink to a certain extent during the process of cooling down to room temperature. If the film shrinks more, the substrate will warp toward the film, and its warp is positive; if the film shrinks less, the substrate will warp away from the film, and its warp is negative. That is to say, the warping of the substrate is caused by the inconsistent expansion coefficients of the film and the substrate. Based on this, the present application corrects or adjusts the degree of warpage of the substrate by forming a thin film on the back of the substrate, thereby reducing the degree of warpage of the substrate so that the robotic arm can hold the substrate and load it Wait for a series of jobs.

The technical solutions of the present invention will be described below in conjunction with the drawings and embodiments.

Referring to FIG. 1 , it is a flowchart of a method for adjusting substrate warpage according to an embodiment of the present invention.

In this embodiment, as shown in FIG. 2 a , a first thin film 22 is formed on the first surface of the substrate 21 , and the first thin film 22 may be formed by deposition, sputtering, or epitaxial growth. When the ambient temperature is lowered from the film growth temperature to room temperature, the substrate 21 warps due to the inconsistent expansion coefficients of the substrate 21 and the first film 22. Assuming that the shrinkage of the first film 22 is greater than that of the substrate 21, it will To form the warpage shown in FIG. 2 b , assuming that the degree of shrinkage of the first film 22 is smaller than the degree of shrinkage of the substrate 21 , the warpage shown in FIG. 2 c will be formed. The method for adjusting the warpage of the substrate may include:

In step 101, the warpage of the substrate is obtained, and a first thin film is formed on the first surface of the substrate.

The calculation of the warpage can be measured by a measurement method in the prior art, for example, by using a bow value (Bowvalue), which can be specifically calculated by calculating the height difference between the highest point and the lowest point of the edge of the substrate after bending.

Step 102, judging whether the absolute value of the warpage of the substrate is greater than or equal to a warpage threshold.

The warpage threshold can be determined according to the adsorption capacity of the robotic arm that adsorbs the substrate and the parameters of the substrate itself. For example, if the warpage of the substrate is greater than or equal to 200um, the robotic arm of the lithography machine cannot If the operation is smooth, the warpage threshold can be determined to be 200um.

In this step, it is judged whether the warpage degree of the substrate is greater than or equal to the warpage degree threshold value, if yes, then proceed to step 103, if not, no further adjustment is made to the warpage degree of the substrate.

Step 103, forming an adjustment film on the second surface of the substrate; the normal direction of the first surface is opposite to the normal direction of the second surface.

As shown in Figures 3a-3b, an adjustment film 23 is formed on the second surface of the substrate 21, wherein the normal direction of the first surface is opposite to the normal direction of the second surface, that is, the adjustment film 23 is opposite to the first film 22. They are respectively located on both sides of the substrate 21 , for example, the first film 22 is located on the front of the substrate 21 , and the adjustment film 23 is located on the back of the substrate 21 , and the stress direction of the adjustment film 23 is consistent with the stress direction of the first film 22 .

The adjustment film 23 can be formed by chemical deposition, sputtering, vapor deposition, epitaxial growth, etc., the expansion coefficient of the adjustment film 23 and the expansion coefficient of the first film 22 are smaller than the expansion coefficient of the substrate 21, or the adjustment film Both the expansion coefficient of the substrate 23 and the expansion coefficient of the first thin film 22 are greater than the expansion coefficient of the substrate 21 .

When the ambient temperature drops to room temperature after the adjustment film 23 is formed, both the adjustment film 23 and the substrate 21 will shrink to a certain extent. To form the degree of substrate warpage as shown in Figure 2b, since the degree of shrinkage of the adjustment film 23 is also greater than the degree of shrinkage of the substrate 21, at this time, as shown in Figure 3a, the shrinkage of the adjustment film 23 will make the substrate The bottom 21 begins to bend toward the adjustment film 23, and the degree of warpage of the final substrate 21 is determined by the degree of shrinkage of the adjustment film 23; if the degree of shrinkage of the first film 22 is smaller than the degree of shrinkage of the substrate 21, a shape as shown in Figure 2c is formed. The degree of warpage of the substrate, because the degree of shrinkage of the adjustment film 23 is also smaller than the degree of shrinkage of the substrate 21, at this time, as shown in FIG. The final warping degree of the substrate 21 is determined by the degree of shrinkage of the adjusting film 23, so that the warping degree of the substrate 21 with the first film 22 can be adjusted or corrected.

When forming the adjustment film 23, the thickness and the number of layers of the adjustment film 23 can be set according to the warpage of the substrate 21. For example, the greater the absolute value of the warpage, the thicker the thickness of the adjustment film 23 is, or the adjustment film 23 can be selected. The expansion coefficient of the material and the expansion coefficient of the substrate are more different to form the adjustment film 23, etc., and the multi-layer adjustment film 23 can also be formed. The multi-layer adjustment film 23 can be of the same material or different materials, as long as the adjustment film is formed. After 23, the warpage of the substrate 21 is adjusted or corrected, so that the warpage of the substrate 21 is less than a warpage threshold, for example, less than 200 um. Adjusting the thickness and material of the film 23 can be obtained through experiments. For example, the thickness of the adjustment film 23 can be set to be the same as that of the first film 22 .

The adjustment film 23 can be a high tensile stress or high pressure stress film, such as silicon nitride film, TiN, W and other films. The substrate in the embodiment of the present invention may be a silicon wafer or other substrates.

In this embodiment, the degree of warpage of the substrate is corrected or adjusted by forming an adjustment film on the substrate, thereby reducing the degree of warpage of the substrate, so that the robotic arm can hold the substrate and load it, etc. Operation. The method is capable of efficiently and controllably adjusting the warpage of the substrate without affecting the original substrate processing technology, ensuring the performance of the product, and enabling the smooth progress of the photolithography process after the thin film deposition.

In the above embodiments, the shape and structure of each component are only examples, not limitations. Moreover, each of the above components can be replaced with other elements with the same function to combine to form more technical solutions, and the technical solutions formed after these replacements should be within the protection scope of the technical solutions of the present invention.

The above descriptions are only preferred embodiments of the present invention, and do not limit the present invention in any form.

Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person familiar with the art, without departing from the scope of the technical solution of the present invention, can use the methods and technical content disclosed above to make many possible changes and modifications to the technical solution of the present invention, or modify it into an equivalent implementation of equivalent changes example. Therefore, any simple modifications, equivalent changes and modifications made to the above embodiments according to the technical essence of the present invention, which do not deviate from the technical solution of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims (5)

1. A method for adjusting substrate warpage, comprising: Obtaining the warpage of the substrate, wherein the first film is formed on the first surface of the substrate; judging whether the absolute value of the warpage of the substrate is greater than or equal to the warpage threshold; If so, forming an adjustment film on the second surface of the substrate so that the warpage of the substrate is less than the warpage threshold, wherein the expansion coefficient of the adjustment film is the same as that of the first film The expansion coefficients are both smaller than the expansion coefficient of the substrate, or, the expansion coefficients of the adjustment film and the first film are both greater than the expansion coefficient of the substrate; the normal direction of the first surface and The normal direction of the second surface is opposite. 2. The method according to claim 1, wherein the warpage threshold is 200 microns. 3. The method according to claim 1, wherein the substrate is a silicon wafer. 4. The method according to any one of claims 1 to 3, characterized in that the adjustment film is a high tensile stress film or a high pressure stress film. 5. The method according to claim 4, wherein the adjustment film is a silicon nitride film, a titanium nitride film or a tungsten metal film.