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KR-102964126-B1 - Method and apparatus for the warpage control of semiconductor wafer

KR102964126B1KR 102964126 B1KR102964126 B1KR 102964126B1KR-102964126-B1

Abstract

A method and apparatus for controlling semiconductor wafer warping are disclosed. The disclosed semiconductor wafer warping control method and apparatus are characterized by focusing a laser beam of a pulsed infrared wavelength inward through the back surface of a semiconductor wafer and forming a modified layer inside the semiconductor wafer using a breakdown phenomenon occurring at the focused portion of the pulsed infrared wavelength laser beam, wherein the height or pattern shape of the modified layer can be changed to control the warping of the semiconductor wafer. Accordingly, the present invention can overcome time, cost, and yield issues compared to conventional thin-film coating methods, and can significantly improve production yield in processes such as ultra-stacking memory production, ultra-fine pattern device fabrication, and wafer-level packaging, where warping is currently a major problem, by controlling the amount of warping.

Inventors

  • 이종명
  • 이홍구

Assignees

  • 주식회사 아이엠티

Dates

Publication Date
20260513
Application Date
20240308

Claims (9)

  1. A method for controlling the warping of a semiconductor wafer used in any one of a multilayer NAND memory fabrication process, a multilayer DRAM memory fabrication process, a fine pattern device fabrication process of 10 nm or less, and a wafer-level packaging process, wherein A step of measuring the degree of warping of the semiconductor wafer using a wafer warping measuring unit - the wafer warping measuring unit measures the degree of warping of the semiconductor wafer by using either a displacement sensor for measuring the height of the semiconductor wafer or a refractometer that determines the degree of warping through the capture of a refraction image - ; A step of protecting the surface of the semiconductor wafer on which a semiconductor device pattern is formed using a protective film; A step of fixing the semiconductor wafer to the wafer chuck such that the back surface of the semiconductor wafer faces upward and the surface of the semiconductor wafer protected by the protective film faces the wafer chuck; A step of focusing a laser beam of pulsed infrared wavelength into the interior through the back surface of a semiconductor wafer; A step of forming a modified layer inside the semiconductor wafer using a breakdown phenomenon occurring at a focused area of the laser beam of the above-mentioned pulsed infrared wavelength; and A semiconductor wafer warping control method characterized by including: a step of controlling the warping of the semiconductor wafer by changing the formation height or pattern shape of the modified layer in correspondence with the degree of warping measured in the step of measuring the degree of warping of the semiconductor wafer.
  2. In claim 1, A semiconductor wafer warping control method characterized in that the laser beam of the above-mentioned pulsed infrared wavelength has a wavelength in the range of 1 μm to 3 μm.
  3. In claim 1, A method for controlling semiconductor wafer warping, characterized in that the laser beam of the above-mentioned pulsed infrared wavelength has a pulse width of 10 ns to 500 nsec and a frequency of 10 kHz to 500 kHz.
  4. In claim 1, A semiconductor wafer warping control method characterized in that the height of the modified layer is formed in an area of 10 to 100 μm on the upper surface of the semiconductor wafer or 10 to 100 μm on the lower surface of the semiconductor.
  5. In claim 1, A semiconductor wafer warping control method characterized in that the shape of the modified layer is any one of an X-axis direction pattern formed along the X-axis direction, a Y-axis direction pattern formed along the Y-axis direction, a grid direction pattern formed along both the X-axis and Y-axis directions, and a local region pattern formed only in a local region.
  6. A semiconductor wafer warping control device for controlling the warping of a semiconductor wafer used in any one of a multilayer NAND memory fabrication process, a multilayer DRAM memory fabrication process, a fine pattern device fabrication process of 10 nm or less, and a wafer level packaging process, A wafer chuck that supports the semiconductor wafer such that, while protecting the surface of the semiconductor wafer on which a semiconductor device pattern is formed using a protective film, the back surface of the semiconductor wafer faces upward and faces the surface of the semiconductor wafer protected by the protective film; A wafer transfer unit for transferring the above semiconductor wafer along the x-axis and y-axis; A laser beam size adjustment unit for adjusting the size of a pulsed infrared laser beam; A laser beam transmission unit that transmits the above pulsed infrared laser beam to the semiconductor wafer side; A laser beam focusing unit for focusing the pulsed infrared laser beam into the interior of the semiconductor wafer to form a laser modification layer inside the semiconductor wafer; and Including an infrared camera for verifying the formation of the laser modified layer; A semiconductor wafer warping control device characterized by measuring the degree of warping of the semiconductor wafer using a wafer warping measurement unit prior to supporting the semiconductor wafer with the wafer chuck, wherein the wafer warping measurement unit measures the degree of warping of the semiconductor wafer using either a displacement sensor for measuring the height of the semiconductor wafer or a refractometer that determines the degree of warping through the capture of a refraction image, and controlling the warping of the semiconductor wafer by changing the formation height or pattern shape of the modified layer in correspondence with the measured degree of warping.
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Description

Method and apparatus for the warpage control of semiconductor wafer The present invention relates to a method and apparatus for controlling wafer warping that inevitably occurs during a semiconductor wafer manufacturing process. Specifically, it relates to a method and apparatus for controlling wafer warping that can control the wafer warping in a desired direction and size by forming a modified layer inside the semiconductor wafer using a pulsed laser beam having an infrared wavelength and controlling the position and shape of the modified layer. Recently, in state-of-the-art semiconductor device manufacturing processes, semiconductor devices are being produced with fine linewidths of 10 nm or less and stacked structures of hundreds of layers or more. During these semiconductor manufacturing processes, numerous heat treatment and thin-film processes are performed. As a result of the continuous accumulation of thermal stress and physical stress caused by differences in the physical properties of the stacked thin films, wafer warping occurs. Pressure is applied to the 3D stacked thin films, causing the wafer to bend and deform like a bow; this phenomenon is also referred to as the wafer bow. In particular, this lowers the Degrees of Field (DoF) and overlay performance during the photolithography process and causes structural deformation, preventing patterns from being properly etched. Figure 1 illustrates that as NAND flash memory advances, the degree of wafer warping increases significantly. Specifically, as the number of layers increases to 32, 48, 64, 96, or 128, the degree of wafer warping increases significantly. Recently, as the number of layers exceeds 200, serious problems such as reduced production yield due to wafer warping are being caused. To solve this wafer warping problem, conventional methods control wafer warping by coating a thin film on the back surface of the wafer to create stress opposite to the direction of warping. However, the additional coating of such thin films to control wafer warping increases the number of coating processes, leading to a significant increase in additional costs and time. Recently, the wafer warping phenomenon has reached a severe level where it can no longer be controlled by this back surface coating process. In addition, wafer warping has become more severe recently as wafers are ground, bonded, and molded during the wafer-level packaging process, but there is currently no method to control this wafer warping. FIG. 1 is a diagram illustrating the problem of semiconductor wafer warping occurring in the semiconductor wafer manufacturing process, and FIG. 2 is a drawing for explaining a method for forming an internal modification layer of a semiconductor wafer according to an embodiment of the present invention, and FIG. 3 is a drawing for explaining a method for controlling wafer warping using an internal modification layer of a semiconductor wafer according to an embodiment of the present invention, and FIG. 4 is a drawing showing examples of pattern shapes for controlling semiconductor wafer warping according to an embodiment of the present invention, and FIG. 5 is a schematic diagram related to semiconductor wafer warping measurement, and FIG. 6 is a schematic diagram of a semiconductor wafer bending control device according to one embodiment of the present invention. Preferred embodiments of the present invention will be described below with reference to the attached drawings. It should be noted that the attached drawings and embodiments are simplified and illustrative for the purpose of assisting those skilled in the art in understanding the present invention. FIG. 2 is a diagram illustrating a method for forming an internal modification layer of a semiconductor wafer according to an embodiment of the present invention, FIG. 3 is a diagram illustrating a method for controlling wafer warping using an internal modification layer of a semiconductor wafer according to an embodiment of the present invention, FIG. 4 is a diagram showing examples of pattern shapes for controlling semiconductor wafer warping according to an embodiment of the present invention, FIG. 5 is a schematic diagram related to measuring semiconductor wafer warping, and FIG. 6 is a schematic diagram of a semiconductor wafer warping control device according to an embodiment of the present invention. In some drawings ( FIG. 2, FIG. 4), a portion of the wafer is shown enlarged, and for convenience, only a portion of the cross-section of the laser modification layer (100) and the wafer (W) is simplified. Although FIG. 2 is a drawing for explaining the present invention, the following applies to FIG. 2 in relation to a conventional wafer cutting process. A pulsed laser beam (110) is focused into the interior of a wafer (W) through a focusing lens (120). When the peak power of the focused pulsed laser beam is sufficiently large, a powerful breakdown phenomenon occurs at the focal point, causing ins