CMP 墊和凹槽的 3D 計量

3D metrology of CMP pads and grooves

CMP墊和凹槽的3D計量

What are CMP pads and why measure them?

什么是CMP墊以及為什么要測量它們？

CMP pads are consumables
used in the
CMP (chemical mechanical polishing or planarization) process
employed in the semi-conductor industry to flatten and polish silicon wafers. The pads are disk shaped, most commonly made from hard and porous polyurethane foam, and patterned with narrow high-aspect-ratio grooves (see image).

CMP墊是用于半導體行業(yè)CMP（化學機械拋光或平面化）工藝的耗材，用于平整和拋光硅晶圓。墊子是圓盤形的，最常見的是由堅硬多孔的聚氨酯泡沫制成，并帶有狹窄的高縱橫比凹槽圖案（見圖）。

The
function of the CMP process
is to improve the performance of silicon wafers, which in turn are used in the development of high-performance microprocessor and memory chips. Since wafers are built up in several layers, each wafer typically undergoes the CMP process several times.

CMP工藝的作用是提高硅片的性能，進而用于開發(fā)高性能微處理器和存儲芯片。由于晶圓由多層構成，因此每個晶圓通常要經(jīng)過多次CMP工藝。

High-precision 3D metrology of CMP pads is required
both in the pad manufacture and during the CMP process to ensure maximum process efficiency and efficacy.

在墊制造和CMP過程中都需要對CMP墊進行高精度3D計量，以確保最大的工藝效率和功效。

CMP pad measurement example – close-up of a 10x10mm square of CMP pad surface, and 3D point cloud data obtained with Novacam SurfaceInspect reveals the depth and shape of the narrow channels down to the micron.

CMP墊測量示例 - 10x10 平方毫米CMP墊表面的特寫，以及使用 Novacam SurfaceInspect 獲得的3D點云數(shù)據(jù)揭示了細至微米的狹窄通道的深度和形狀。

How does the CMP process work?

CMP流程如何運作？

In the CMP process:

在CMP過程中：

The
silicon wafer
is mounted on a rotating
wafer carrier
and pressed against a
CMP pad
affixed on a rotating
platen.

硅晶片安裝在旋轉的晶片載體上，并壓在旋轉臺板上的CMP墊上。

At the same time, ultra-fine chemical
polishing slurry
is sprayed onto and channeled around the pad surface. Slurry distribution is done via tiny narrow
grooves
machined in specific patterns on the CMP pad surface.

同時，將超細化學拋光漿噴涂到墊表面并在其周圍形成通道。漿料分布是通過在CMP墊表面上以特定圖案加工的微小窄槽完成的。

The corrosiveness of the slurry together with the asperities on the CMP pad surface wear away the wafer surface until the desired flatness and polish are achieved.

研磨液的腐蝕性與 CMP 墊表面的粗糙度一起磨損晶圓表面，直到達到所需的平整度和拋光度。

To extend the lifespan of the CMP pad, the pad is typically reconditioned on a continuous or intermittent basis.
This is done using a
pad conditioner, which slices and pops open newly uncovered bubbles in the pad with diamond tips on its surface.

為了延長CMP墊的使用壽命，通常會連續(xù)或間歇地修復墊。這是使用墊調(diào)節(jié)器完成的，該調(diào)節(jié)器將墊中新發(fā)現(xiàn)的氣泡切成薄片并彈出，其表面帶有金剛石尖端。

Simplified diagram of CMP (Chemical Mechanical Planarization/Polishing) process

CMP（化學機械平面化/拋光）工藝簡圖

Why is quality control of CMP pads crucial?

為何CMP墊的質(zhì)量控制至關重要？

First, both the silicon wafer and the CMP pads are costly items.

首先，硅片和CMP墊都是昂貴的物品。

Second, the geometry and condition of CMP pad surfaces greatly affects CMP process efficacy.

其次，CMP墊表面的幾何形狀和條件極大地影響CMP工藝效果。

For example, the
grooves on CMP pads
must be measured because the pattern, depth, and shape of these tiny channels influence slurry consumption and distribution, material removal rate (MRR), the rate of accumulation of polishing debris, as well as potential creation of scratches on wafers by this debris.

例如，必須測量CMP墊上的凹槽，因為這些微小通道的圖案、深度和形狀會影響研磨液的消耗和分布、材料去除率 (MRR)、拋光碎屑的積累速率以及潛在的拋光這些碎屑在晶圓上造成劃痕。

Zoom-in view of one of a CMP pad groove with tool marks on the groove bottom readily visible. Measurements are in mm.

放大CMP 墊凹槽的一個視圖，凹槽底部的工具標記清晰可見。測量單位為毫米。

3D measurements for CMP pad manufacture and CMP process in general

一般CMP墊制造和CMP工藝的3D測量

Novacam 3D metrology systems are uniquely suitable to carry out fast, high-precision 3D metrology of:

Novacam 3D測量系統(tǒng)特別適合執(zhí)行快速、高精度的3D測量：

CMP pads, including the hard-to-measure grooves and lands (the surface between the grooves)

CMP墊，包括難以測量的凹槽和平臺（凹槽之間的表面）

CMP pad conditioners

CMP墊調(diào)節(jié)器

Wafers, including their flatness.

晶圓，包括其平整度。

Novacam systems’ capabilities include:

Novacam 系統(tǒng)的功能包括：

Non-contact 3D surface measurements with 1 μm (40 μin.) axial resolution

具有 1 μm（40 μin.）軸向分辨率的非接觸式3D表面測量

Ability to scan high-aspect-ratio features such as the narrow CMP pad grooves

能夠掃描高縱橫比特征，例如狹窄的CMP墊槽

High-speed surface acquisition – up to 100,000 3D measurements/sec

高速表面采集——高達10萬次3D測量/每秒

Dimensional and roughness measurements with the same probe

使用同一探頭進行尺寸和粗糙度測量

Ability to obtain long profiles

能夠獲得較長的配置文件

Facility for automated measurement both in lab and in high-volume automated production.

在實驗室和大批量自動化生產(chǎn)中進行自動化測量的設施。

View from below of the CMP pad grooves clearly shows the tool marks of the bit used to machine the channels. Perfect cylinders were fitted on each groove to obtain a mean radius measurement. Here, the measured radii of curvature were found to vary between 475 and 528 μm

CMP墊槽下方的視圖清楚地顯示了用于加工通道的鉆頭的工具標記。完美的圓柱體安裝在每個凹槽上以獲得平均半徑測量值。在這里，測得的曲率半徑在475~ 528 μm之間變化

文件：AN-THICKNESS-1.2（2021-06-03）

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