Taper
Silicon Trench
Dห้องสมุดไป่ตู้agram
5
刻蚀的主要指标
• 刻蚀偏差是指刻蚀以后线宽或关键尺寸间 距的变化。通常由于横向刻蚀引起，但也 可能由刻蚀剖面引起。
Wb Wa
Resist
Bias 刻蚀偏差=Wb-Wa
Bias Resist
Film
Film
Substrate (a)
Substrate
CD Control
Fair/good
Poor
* Used primarily for stripping and etchback operations.
Poor to nonexistent
Good/excellent
12
平板反应器
• 平板反应器有两个大小和位置对称的平行 金属板，一个硅片背面朝下放在接地的阴 极上面，RF信号加在反应器的上电极。
(b)
6
横向钻蚀
Undercut
Overetch
Resist Film Substrate
7
刻蚀的主要指标
• 选择比是指在同一条件下一种材料与另一 种材料相比刻蚀速率快多少。
Ef S=
Er
Er
Ef
Nitride
Oxide
8
刻蚀的主要指标
• 均匀性
深宽比相关刻蚀：刻蚀速率在小窗口图形 中较慢，甚至在具有高深宽比的小尺寸图 形上刻蚀停止。
Matching network
RF generator
Gas- flow controller
Gas dispersion screen
Gas panel Electrodes
Roots pump
Microcontroller Operator Interface
Endpoint signal
Wafer Pressure controller
干法刻蚀机理
Physical Etching
Sputtered surface material
Reactive +ions bombard surface
Chemical Etching
Surface reactions of radicals + surface film
Desorption of by-products
5) Adsorption of reactive ions on surface
6) Surface reactions of
7) Desorption of
radicals and surface film by-products
Substrate
Isotropic etch
Cathode
在半导体生产中， 干法刻蚀是最主要的用来去除表面材料的刻蚀方法10。
surface*
wafer surface
In dry etch, etching includes ion sputtering and radicals reacting with wafer surface
Sidewall Profile Selectivity
Anisotropic
Poor/difficult to increase (1:1)
Randomly select 3 to 5 wafers in a lot
Measure etch rate at 5 to 9 locations on each wafer, then calculate etch uniformity for each wafer and compare wafer-to-wafer.
(b) Substrate after etch
2
刻蚀的主要指标
• 刻蚀速率，通常用A/min来表示 负载效应
T = change in thickness
T
t = elapsed time during etch
Start of etch
End of etch
3
刻蚀的主要指标
• 刻蚀剖面：各向同性和各向异性两种
Isotropic etch - etches in all directions at the same rate
Anisotropic etch etches in only one
direction
Resist
Resist
Film Substrate
Film Substrate
4
刻蚀侧壁剖面
Chemical Etch
Combined Physical and
Chemical
Physical ion sputtering
Etch Mechanism
Radicals in Radicals in
plasma reacting liquid (?)
with wafer
reacting with
第十章 刻蚀技术
1
刻蚀的目的
• 刻蚀是用物理或化学方法有选择地从硅片 表面去除不需要的材料的过程。
• 两种基本刻蚀工艺：干法和湿法
Photoresist mask
Photoresist
Film
mask
to be etched
Protected film
(a) Photoresist-patterned substrate
Isotropic
Isotropic
Isotropic to Anisotropic
Fair/good (5:1 Good/excellent Fair/good
to 100:1)
(up to 500:1) (5:1 to 100:1)
Etch Rate
High
Moderate
Low
Moderate
Type of Etch Sidewall Profile
Wet Etch Dry Etch
Isotropic
Isotropic (depending on equipment &
parameters) Anisotropic (depending on equipment & parameters) Anisotropic –
Pressure signal
Exhaust
Roughing
pump
13
Process gases
氟化胺
14
15
硅的各向同性腐蚀
• 对于半导体材料，湿法化学刻蚀通常是先进行氧 化反应，在通过化学反应溶解氧化物。
• 硅常见刻蚀液是：硝酸+氢氟酸+醋酸 氧化过程：
Si 4HNO3 SiO2 2H2O 4NO2
Anisotropic etch
Electric field
Anode Etch process chamber
l
3) Recombination of electrons with atoms creates plasma
l
By-products
8) By-product removal
Exhaust
氢氟酸用于溶解氧化硅：
SiO2 6HF H2SiF6 2H2O
醋酸能够减少硝酸分解
16
17
18
19
20
21
微悬臂梁(表面MEMS）
22
23
微化学离子传感器
24
Anisotropic etch
Isotropic etch
11
各种干法刻蚀方法的比较
Etch Parameter
Physical Etch (RF field
perpendicular to wafer surface)
Physical Etch (RF field parallel to
wafer surface)
9
干法刻蚀（等离子体刻蚀过程）
RF generator
1) Etchant gases enter chamber
Gas delivery
2) Dissociation of reactants by electric fields
4) Reactive +ions bombard surface