CN108628109B

CN108628109B - Photoetching exposure equipment and photoetching exposure method

Info

Publication number: CN108628109B
Application number: CN201810418147.0A
Authority: CN
Inventors: 刘必秋
Original assignee: Shanghai Huali Integrated Circuit Manufacturing Co Ltd
Current assignee: Shanghai Huali Integrated Circuit Manufacturing Co Ltd
Priority date: 2018-05-04
Filing date: 2018-05-04
Publication date: 2021-06-15
Anticipated expiration: 2038-05-04
Also published as: CN108628109A

Abstract

The invention relates to a photoetching exposure device, which relates to the integrated circuit manufacturing technology, and comprises a light source, a mask plate and a wafer, wherein the mask plate is positioned between the light source and the wafer, the light source is used for emitting light beams to irradiate the mask plate, and the light source emits light beams with at least two bandwidths; so that the process windows of the photoetching exposure equipment aiming at different areas of the mask are maximized, and the whole process window of the photoetching process is further improved.

Description

Photoetching exposure equipment and photoetching exposure method

Technical Field

The invention relates to an integrated circuit manufacturing technology, in particular to a photoetching exposure device with a good whole process window.

Background

The semiconductor industry is always looking for integrated circuit products with higher integration, and to increase the integration of integrated circuits, the critical dimension is continuously reduced, and the designed patterns are more and more complex. Photolithography is the most critical process step in all basic semiconductor manufacturing processes. The photolithography technique transfers the pattern on the mask to the photoresist on the surface of the wafer by using ultraviolet light, then displays the pattern in the photoresist by photolithography development, and then images the pattern on the wafer below the photoresist by using an etching process, so that the size of the critical dimension of the pattern imaged on the wafer is closely related to the photolithography process.

For a photolithography process flow satisfying the mass production of devices, all patterns on the mask plate need to be clearly analyzed, and enough process windows need to be ensured. The process window represents the capability of keeping stable and clearly analyzing the graph when the process is subjected to various perturbations in the photoetching process. A larger process window indicates a relatively stronger resistance to external perturbations and a relatively better process stability. Since the patterns in the mask are designed according to the circuit diagram of the integrated circuit, the circuit diagram of the integrated circuit is greatly different in different areas. Specifically, please refer to fig. 1A, 1B, 1C and 1D, in which fig. 1A is a schematic diagram of a dense pattern region, fig. 1B is a schematic diagram of a sparse pattern region, fig. 1C is a schematic diagram of an isolated pattern region, and fig. 1D is a schematic diagram of a complex pattern region. As shown in fig. 1A, in a certain area S, there are a large number of pattern areas 10 and a large number of light blocking areas 20, and the pattern areas 10 and the light blocking areas 20 are arranged according to a certain rule, and the pattern areas 10 are called dense pattern areas because they are relatively dense. As shown in fig. 1B, in a certain area S, there are a certain number of pattern regions 10 and a certain number of light blocking regions 20, and the pattern regions 10 and the light blocking regions 20 are arranged according to a certain rule, but the number of pattern regions 10 is small, and therefore, they are called sparse pattern regions. As shown in fig. 1C, only one pattern region 10 exists in a certain area S, and thus is referred to as an isolated pattern region. As shown in fig. 1D, the pattern region 10 and the light blocking region 20 are irregularly arranged in a certain area S, i.e., are not regularly arranged, and thus are called as a complex pattern region. Under the condition that a light source is fixed, process windows of a dense pattern area, a complex pattern area, a sparse pattern area and an isolated pattern area are greatly different, and the whole process window of the existing photoetching process is restricted.

In the prior art, a process window detection method (PWQ) is designed to detect hot spot patterns of a lithography process, an optical proximity effect (OPC) is revised for the patterns, a re-published mask is updated based on the optical proximity effect (OPC) revision, and multiple cycles are performed to ensure that all the patterns have enough process windows. However, this method requires a lot of labor and cost, and may require such cyclic verification for different products, and the space for adjusting the optical proximity effect (OPC) correction is limited, and cannot achieve the desired target for some special patterns and meet the production requirements.

Therefore, in the fabrication of integrated circuits, there is a need to devise a method for improving the overall process window of the photolithography process.

Disclosure of Invention

The invention aims to provide a photoetching exposure device, so as to obtain a photoetching exposure device with a better whole process window.

The invention provides a lithographic exposure apparatus comprising: the light source is used for emitting light beams to irradiate the mask plate, wherein the light source emits light beams with at least two bandwidths.

Furthermore, the mask plate comprises a first type of pattern area and a second type of pattern area, and the bandwidth of the light beam irradiating the first type of pattern area is different from the bandwidth of the light beam irradiating the second type of pattern area.

Furthermore, the first type of pattern area is a dense pattern area, the second type of pattern area is a sparse pattern area, a complex pattern area or an isolated pattern area, and the bandwidth of the light beam irradiating the second type of pattern area is smaller than the bandwidth of the light beam irradiating the first type of pattern area.

Furthermore, the bandwidth of the light beam emitted by the light source ranges from 50 to 350 fm.

Furthermore, the lithography exposure equipment is an ArF lithography machine or an EUV lithography machine.

The invention further provides a photoetching exposure method, which comprises the following steps: step S1, providing an exposure program to the light source of the photolithography exposure apparatus; step S2, irradiating the mask plate by the exposure program, and transferring the pattern on the mask plate to the surface of the wafer; step S3, detecting whether a hot spot pattern exists on the surface of the wafer by a defect detection means; and step S4, judging whether the wafer surface has a hot spot pattern, if so, entering step S5, if not, entering step S6, wherein, if step S5 is, setting an updated light beam bandwidth to the exposure program aiming at the hot spot pattern, at the moment, the exposure program instructs the light source to emit light beams with at least two bandwidths, and entering step S2; in step S6, the exposure program in step S2 is used to perform the photolithography exposure process for mass production of products.

Further, the defect detecting means includes scanning the surface of the wafer with a defect scanning apparatus.

Furthermore, the step S6 further includes a step S61, in which the number of times of switching the bandwidth of the light beam is N when performing the photolithography exposure process for mass production of products, where N is greater than or equal to 1.

Furthermore, the bandwidth of the light beam is in a range of 50-350 fm.

Further, the exposure program in step S1 instructs the light source to emit a light beam including a bandwidth.

According to the photoetching exposure equipment and the whole process window optimization method thereof, the photoetching exposure equipment optimizes the process window of each graphic area on the mask by emitting light beams with different bandwidths aiming at different graphic areas on the mask, so that the whole process window is improved.

Drawings

FIG. 1A is a schematic diagram of a dense pattern area.

FIG. 1B is a schematic view of a sparse pattern area.

FIG. 1C is a schematic diagram of isolated pattern regions.

FIG. 1D is a schematic diagram of a complex graphics area.

FIG. 2 is a schematic view of a lithographic exposure apparatus according to an embodiment of the invention.

FIG. 3 is a waveform diagram of beam bandwidth and process window and critical dimensions according to an embodiment of the present invention.

FIG. 4 is a flowchart of a photolithography exposure method according to an embodiment of the present invention.

FIG. 5 is a diagram illustrating the distribution of the photolithographic reticle and the beam bandwidth according to an embodiment of the present invention.

Fig. 6 is a schematic diagram illustrating a relationship between a hot spot pattern and a process window according to an embodiment of the invention.

The reference numerals of the main elements in the figures are explained as follows:

100. a light source; 200. a mask plate; 300. a wafer; 110. a light beam.

Detailed Description

Referring to FIG. 2, FIG. 2 is a schematic diagram of a photolithography exposure apparatus according to an embodiment of the invention. As shown in fig. 2, the photolithography exposure apparatus according to an embodiment of the present invention includes a light source 100, a mask 200 and a wafer 300, wherein the mask 200 is located between the light source 100 and the wafer 300. The mask 200 is mainly made of transparent quartz and is embedded with opaque chrome to form a pattern. During exposure, the light beam 110 is emitted from the light source 100 to irradiate the reticle 200, and the pattern on the reticle 200 is transferred to the surface of the wafer 300 to complete the photolithography exposure process. Further, the light source 100 emits light beams with at least two bandwidths, for example, in one embodiment, the light source 100 emits light beams with bandwidths different from those of light beams emitted when scanning a region with sparse or isolated patterns on the reticle 200 and light beams emitted when scanning a region with dense patterns on the reticle 200.

Therefore, according to the photoetching exposure equipment, the light source emits light beams with different bandwidths to carry out photoetching process, so that the process windows of different areas of the mask are maximized, and the whole process window of the photoetching process is further improved.

Referring to fig. 3, fig. 3 is a waveform diagram of a beam bandwidth, a process window and a critical dimension according to an embodiment of the invention. As shown in fig. 3, the process window and the critical dimension of the dense pattern region on the reticle 200 do not change much with the bandwidth of the light beam 110, but the process window of the sparse pattern region on the reticle 200 increases with the bandwidth of the light beam 110, and the critical dimension also increases with the bandwidth of the light beam 110. However, in integrated circuit fabrication, it is desirable that the critical dimension is continuously reduced and the process window is continuously enlarged, so that each region needs to select the corresponding bandwidth of the light beam according to the pattern condition to obtain the desired process window and critical dimension. With the development of integrated circuits, the integration level of the integrated circuits is higher and higher, the number of integrated components of a single chip even reaches billions, and the complexity of the integrated circuits is higher and higher, a pattern on a mass-produced integrated circuit may include a plurality of dense pattern regions, complex pattern regions, sparse pattern regions and isolated pattern regions, the pattern density or sparsity of each region is different, the dense pattern regions may be called first type pattern regions, the complex pattern regions, the sparse pattern regions and the isolated pattern regions may be called second type pattern regions, different pattern regions have different process windows and key sizes relative to light beams with the same bandwidth, and the change rate along with the change of the bandwidth of the light beams is different. Therefore, in an embodiment of the present invention, the light source 100 emits light beams 110 with different bandwidths to irradiate different regions of the mask 200, so as to optimize the process window and the critical dimension of each region, thereby obtaining a better overall process window, reducing the number of hot spot patterns, reducing the number of optical proximity effect (OPC) corrections and mask reissuing times, and saving the time and cost of developing the photolithography process. As shown in fig. 3, in an embodiment of the present invention, the bandwidth of the light beam irradiating the sparse pattern region is smaller than that of the light beam irradiating the dense pattern region, and the isolated pattern region and the complex pattern region are similar to the sparse pattern region and use a smaller bandwidth.

Referring to fig. 4, fig. 4 is a flowchart of a photolithography exposure method according to an embodiment of the present invention. The method for optimizing the whole process window of the photoetching exposure equipment comprises the following steps: in step S1, an exposure program is provided to the light source 100 of the lithography exposure apparatus. The exposure program includes a preset beam bandwidth distribution map corresponding to the pattern status of different areas on the reticle 200. Specifically, referring to fig. 5, fig. 5 is a schematic diagram of a distribution of a photolithography mask and a beam bandwidth according to an embodiment of the present invention. As shown in fig. 5, the X-axis and the Y-axis define different regions of the photolithography mask 200, such as a1, a2, A3, and a4, where the different regions represent different pattern conditions, i.e., different exposure regions, and the Z-axis corresponds to the bandwidth of the light beam. As shown in fig. 5, the light beam bandwidths corresponding to different exposure regions are different, so as to optimize the process window of each region, and further, obtain a better overall process window. Of course, the exposure program at this time indicates that the light beam 110 emitted from the light source 100 may include one bandwidth or a plurality of bandwidths. In step S2, the reticle 200 is irradiated with the exposure program to transfer the pattern on the reticle 200 to the surface of the wafer 300. In step S3, the defect detection means detects whether there is a hot spot pattern (i.e. an area with insufficient process window) on the surface of the wafer 300. Step S4, determining whether a hot spot pattern exists on the surface of the wafer, if so, entering step S5, setting an updated beam bandwidth for the hot spot pattern into an exposure program, wherein the exposure program instructs a light source to emit beams with at least two bandwidths, and entering step S2. More specifically, referring to fig. 6, fig. 6 is a schematic diagram illustrating a relationship between a hot spot pattern and a process window according to an embodiment of the invention. As shown in fig. 6, the abscissa is the amplitude of the focal depth of exposure, the ordinate is the latitude (%) of exposure, the focal depth amplitude of the light beam under a specific bandwidth-the area of the area surrounded by the latitude characteristic curve of exposure and the abscissa and the ordinate represents the process window, the larger the area, the larger the process window is represented, as shown in fig. 6, the process window of a certain hot spot pattern under the light beam with 200 bandwidth is larger than the process window under the light beam with 300 bandwidth, so that different beam bandwidth correction values can be set to the exposure program according to different hot spot patterns. If there is no hot spot pattern, the process proceeds to step S6, and the exposure program in step S2 is used to perform the photolithography exposure process for mass production of products. The optimization is repeated to generate the optimal beam bandwidth and the distribution graph between the photoetching masks (figure 5), and the exposure program of the photoetching exposure equipment is formed. When the lithography exposure equipment is exposed, the bandwidth of the light beam 110 of the light source 100 is switched according to the exposure program, namely the distribution diagram between the bandwidth of the light beam and the lithography mask plate, and the hot spot pattern process window is optimized, so that the whole process window is improved, and the production requirement is met. In an embodiment of the present invention, the step S6, performing the photolithography exposure process for mass production products by using the exposure program in the step S2, further includes a step S61, wherein the number of times of switching the bandwidth of the light beam 110 is N times when performing the photolithography exposure process for mass production products, where N is greater than or equal to 1, that is, the light source 100 emits light beams with at least two bandwidths in the exposure process. In an embodiment of the present invention, the switching range of the bandwidth of the light beam 110 is 50 to 350fm, and certainly, a wider bandwidth range of the light beam 110 may be set according to requirements of different products, which is not limited in the present invention.

In an embodiment of the present invention, in step S3, the defect detecting means is used to detect whether there is a hot spot pattern on the surface of the wafer 300, wherein the defect detecting means includes scanning the surface of the wafer 300 by using a defect scanning device, which is not limited in the present invention, and other defect detecting means are all suitable for the present invention.

In an embodiment of the present invention, the lithography exposure apparatus of the present invention may be applied to an ArF lithography machine and an EUV lithography machine, and the present invention is not limited to the specific type of the lithography machine, and is applicable to lithography machines in which the bandwidth of all light beams is adjustable.

To sum up, the photolithography exposure equipment optimizes the process window of each pattern region on the mask by emitting light beams with different bandwidths aiming at different pattern regions on the mask, thereby improving the whole process window.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lithographic exposure apparatus, comprising: the mask is positioned between the light source and the wafer, the light source is used for emitting light beams to irradiate the mask, wherein the light source comprises an exposure program, the exposure program comprises a preset light beam bandwidth distribution diagram, the light beam bandwidth distribution diagram corresponds to the graph conditions of different areas on the mask, the graph conditions of the different areas on the mask comprise a first type graph area and a second type graph area, the first type graph area is a dense graph area, the second type graph area is a sparse graph area, a complex graph area or an isolated graph area, the process windows of the first type graph area and the second type graph area are different under the condition that the light source is fixed, the light source emits light beams with at least two bandwidths, and the light beams with each bandwidth correspond to the first type graph area so as to improve the process windows of the graph conditions of the different areas on the mask, wherein the bandwidth of the light beam illuminating the second type of pattern area is smaller than the bandwidth of the light beam illuminating the first type of pattern area.

2. The lithographic exposure apparatus of claim 1, wherein the bandwidth of the light beam emitted by the light source is in the range of 50-350 fm.

3. A lithographic exposure method, comprising:

step S1, providing an exposure program to the light source of the photoetching exposure equipment, wherein the exposure program comprises a preset light beam bandwidth distribution diagram which corresponds to the graph status of different areas on the mask, wherein the graph status of the different areas on the mask comprises a first class graph area and a second class graph area, the first class graph area is a dense graph area, the second class graph area is a sparse graph area, a complex graph area or an isolated graph area, and under the condition that the light source is fixed, the process windows of the first class graph area and the second class graph area are different, and at this time, the exposure program indicates the light source to emit a light beam with a bandwidth;

step S2, irradiating the mask plate by the exposure program, and transferring the pattern on the mask plate to the surface of a wafer;

step S3, detecting whether a hot spot pattern exists on the surface of the wafer by a defect detection means; and

step S4, judging whether the wafer surface has a hot spot pattern, if yes, entering step S5, and if not, entering step S6;

step S5 is, setting an updated light beam bandwidth to the exposure program for the hot spot pattern, where the exposure program instructs the light source to emit light beams with at least two bandwidths, and each of the light beams with one bandwidth corresponds to one type of pattern region to improve the process window of the pattern condition in different regions on the mask, and then step S2 is performed; step S6 is executed to perform a photolithography exposure process for mass production of products by the exposure program in step S2, wherein the bandwidth of the light beam irradiating the second pattern region is smaller than the bandwidth of the light beam irradiating the first pattern region.

4. The lithographic exposure method of claim 3, wherein the defect detection means comprises scanning the wafer surface with a defect scanning device.

5. The photolithography exposure method according to claim 3, wherein the step S6 further includes a step S61, wherein the number of times of switching the bandwidth of the light beam is N when performing the photolithography exposure process for mass production of products, wherein N is greater than or equal to 1.

6. The photolithographic exposure method of claim 5, wherein the bandwidth of the beam is in the range of 50-350 fm.